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- Front Matter: Volume 7014
- Instrumentation at Major Observatories I
- Instrumentation at Major Observatories II
- Optical Imaging
- Optical Spectroscopy
- Infrared Cameras and Spectrometers
- Airborne Instruments
- Solar Instruments
- Adaptive Optics Fed Instrumentation and High Contrast Imaging I
- Instruments for ELTs I
- Instruments for ELTs II
- Instrumentation Techniques and Technologies I
- Instrumentation Techniques and Technologies II
- Instrumentation Techniques and Technologies III
- Posters: UV/VIS/IR Instrumentation
- Posters: Instrumentation Techniques and Technologies
Front Matter: Volume 7014
Front Matter: Volume 7014
Show abstract
This PDF file contains the front matter associated with SPIE Proceedings Volume 7014, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.
Instrumentation at Major Observatories I
Instrumentation at the W. M. Keck Observatory
Show abstract
Developing new instruments and upgrading existing systems continues to be an important part of our science driven
strategic plan at the W. M. Keck Observatory, now in its 14th year of operation. Our emphasis remains on high angular
resolution astronomy and faint-object spectroscopy. The instrument development program is now in its third generation.
The first of these, OSIRIS, was delivered in February 2005 and together with NIRC2 is now in routine operation with
the laser guide star adaptive optics (LGS AO) system on the Keck II telescope. During 2007 new wave front controllers
were installed in the Keck I and Keck II AO systems and over 70 nights per semester are now allocated to AO science.
WMKO is collaborating with the Gemini Observatory on the development of a solid state laser for the Keck I telescope.
The V2 mode of the Keck Interferometer is offered for routine observing and the 10 micron Nuller is now being used for
the NASA exo-zodiacal dust survey key project. The atmospheric dispersion corrector (ADC) for the Cassegrain focus
of the Keck I telescope was installed in 2007 and is now in routine use. In addition, a detector upgrade is under way for
the red channel of the LRIS instrument on Keck I. Our next third generation instrument will be MOSFIRE, a near-IR
multi-object spectrograph, which is currently in the fabrication phase. A Visitor Port on Keck I is now ready to receive
instruments, with the first one expected to be NIRES, a cross-dispersed echellette instrument for the near-infrared.
Deployment of a large suite of new acquisition, guiding and image quality monitoring systems to replace all the existing
CCD guiders and acquisition cameras at the Observatory is also under way. The first system has been retro-fitted to
NIRSPEC. Finally, studies are in progress on the development of a next generation AO system and an associated suite of
instruments, and there has been a recent call for concepts for new seeing-limited instruments.
Instrumentation at the ESO VLT
Show abstract
ESO's Very Large Telescope (VLT) on Paranal mountain in northern Chile comprises four 8.2m diameter 'Unit
Telescopes' (also used for interferometry); four 1.8m movable outrigger telescopes dedicated to interferometry and two
survey telescopes - the 2.6m VST to be used in the visible and the 4m class, infrared VISTA telescope. Here I will give
an overview of the accompanying large instrument development programme which has so far delivered 11 operational
facility instruments for the UT's (leaving one visitor Nasmyth focus) and 2 major instruments for the interferometric
focus. In addition, a laser guide star facility has been added on UT4 to generate artificial (sodium) stars for the adaptive
optics assisted instruments NACO and SINFONI; the optical and infrared cameras for the survey telescopes are almost
ready; four major second generation instruments for the UTs (X-Shooter, KMOS, MUSE and SPHERE) are at various
stages of development throughout Europe; a fifth (high resolution spectrograph capable of 10cm/s radial velocity
stability at the incoherent combined focus of the four 8m telescopes) is the subject of a Call for Proposals; UT4 is being
converted to a fully adaptive telescope and three second generation interferometric instruments (MATISSE, GRAVITY
and VSI) have been approved following successful completion of their Phase A studies.
The status and future plan of Subaru Telescope instruments
Show abstract
The first generation instruments of Subaru are seven plus one Cassegrain AO system. After the nearly ten
year operation, the second generation instrument construction has been conducted. MOIRCS, 7' × 4' FOV NIR
multi-object camera and spectrograph has been in operation from 2005, and is now most popular instrument
of Subaru. A LGS AO system at Nasmyth focus (AO188) had the first light in 2006. HiCIAO; near IR high
dynamic range coronagraph instrument working with AO188 for exoplanet detection had recently the first
light. FMOS; fiber multi-object spectrograph with 400 fibers is now in commissioning phase. Hyper Suprime-
Cam with 1.5 degree FOV at the prime focus is now being developed and will be in operation in 2012.
Current and future facility instruments at the Gemini Observatory
Show abstract
At the present time, several new Gemini instruments are being delivered and commissioned. The Near-Infrared Coronagraph has been extensively tested and commissioned on the Gemini-South telescope, and will soon begin a large survey to discover extrasolar planets. The FLAMINGOS-2 near-IR multi-object spectrograph is nearing completion at the University of Florida, and is expected to be delivered to Gemini-South by the end of 2008. Gemini's Multi-Conjugate Adaptive Optics bench has been successfully integrated and tested in the lab, and now awaits integration with the laser system and the Gemini-South AO Imager on the telescope. We also describe our efforts to repair thermal damage to the Gemini Near-IR Spectrograph that occurred last year. Since the last update, progress has been made on several of Gemini's next generation of ambitious "Aspen" instruments. The Gemini Planet Imager is now in the final design phase, and construction is scheduled to begin shortly. Two competitive conceptual design studies for the Wide-Field Fiber Multi-Object Spectrometer have now started. The Mauna Kea ground layer monitoring campaign has collected data for well over a year in support of the planning process for a future Ground Layer Adaptive Optics system.
Present and future instrumentation for the Hobby-Eberly Telescope
Show abstract
The Hobby-Eberly Telescope (HET) is an innovative large telescope of 9.2 meter aperture, located in West Texas at
McDonald Observatory. The HET operates with a fixed segmented primary and has a tracker which moves the four-mirror
corrector and prime focus instrument package to track the sidereal and non-sidereal motions of objects. The
HET has been taking science data for nearly a decade. Recent work has improved performance significantly, replacing
the mirror coatings and installing metrology equipment to provide feedback that aids tracking and alignment of the
primary mirror segments. The first phase of HET instrumentation included three facility instruments: the Low
Resolution Spectrograph (LRS), the Medium Resolution Spectrograph (MRS), and High Resolution Spectrograph
(HRS). The current status of these instruments is briefly described.
A major upgrade of HET is in progress that will increase the field of view to 22 arcminutes diameter, replacing the
corrector, tracker and prime focus instrument package. This wide field upgrade will feed a revolutionary new integral
field spectrograph called VIRUS, in support of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX).
VIRUS is a facility instrument that consists of 150 or more copies of a simple unit integral field spectrograph. In total
VIRUS will observe 34,000 spatial elements simultaneously, and will open up wide-area surveys of the emission-line
universe for the first time. We describe the HET wide field upgrade and the development of VIRUS, including results
from testing the prototype of the VIRUS unit spectrograph.
Commissioning of the Southern African Large Telescopes (SALT) first-generation instruments
Show abstract
The Southern African Large Telescope is nearing the end of its commissioning phase and scientific performance
verification programmes began in 2006 with two of its First Generation UV-visible instruments, the imaging camera,
SALTICAM, and the multi-mode Robert Stobie Spectrograph (RSS). Both instruments are seeing limited and designed to
operate in the UV-visible region (320 - 900 nm). This paper reviews the innovative aspects of the designs of these
instruments and discusses the commissioning experience to date, illustrated by some initial scientific commissioning
results. These include long-slit and multi-object spectroscopy, spectropolarimetry, Fabry-Perot imaging spectroscopy and
high-speed photometry. Early spectroscopic commissioning results uncovered a serious underperformance in the
throughput of RSS, particularly at wavelengths < 400nm. We discuss the lengthy diagnosis and eventual removal of this
problem, which was traced to a material incompatibility issue involving index-matching optical coupling fluid. Finally,
we briefly discuss the present status of the third and final First Generation instrument, a vacuum enclosed fibre-fed high
resolution, dual beam, white pupil echelle spectrograph, SALT HRS, currently under construction.
The GTC facility instruments: a status review
Show abstract
The Gran Telescopio Canarias (GTC) 10.4m telescope received its First Light on July 13, 2007. At present the GTC is
undergoing commissioning tests. Night time observations are being carried out routinely from Monday through to
Thursday every week. The GTC will begin science observation by the end of the year, and will be offered to the
community in September 2008 for the semester starting in March 09. The two first generation science instruments are
getting ready to be mounted on the telescope. In this talk I will go through the main features of the first generation
science instruments and describe their status of completion. I will also devote some time to the second-generation
instruments that are currently at various states of advancement. These include EMIR, a wide field multi-object K band
cryogenic spectrograph, and FRIDA, which is a near IR Adaptive Optics fed integral field spectrograph. Finally, I will
describe a set of smaller instruments that will complement and indeed extend the observing capabilities of the GTC soon
after the start of science operation.
An overview of instrumentation for the Large Binocular Telescope
Show abstract
An overview of instrumentation for the Large Binocular Telescope is presented. Optical instrumentation includes
the Large Binocular Camera (LBC), a pair of wide-field (27' × 27') mosaic CCD imagers at the prime focus, and
the Multi-Object Double Spectrograph (MODS), a pair of dual-beam blue-red optimized long-slit spectrographs
mounted at the straight-through F/15 Gregorian focus incorporating multiple slit masks for multi-object spectroscopy
over a 6 field and spectral resolutions of up to 8000. Infrared instrumentation includes the LBT Near-IR
Spectroscopic Utility with Camera and Integral Field Unit for Extragalactic Research (LUCIFER), a modular
near-infrared (0.9-2.5 μm) imager and spectrograph pair mounted at a bent interior focal station and designed
for seeing-limited (FOV: 4' × 4') imaging, long-slit spectroscopy, and multi-object spectroscopy utilizing cooled
slit masks and diffraction limited (FOV: 0.5' × 0.5') imaging and long-slit spectroscopy. Strategic instruments
under development for the remaining two combined focal stations include an interferometric cryogenic beam combiner
with near-infrared and thermal-infrared instruments for Fizeau imaging and nulling interferometry (LBTI)
and an optical bench near-infrared beam combiner utilizing multi-conjugate adaptive optics for high angular
resolution and sensitivity (LINC-NIRVANA). In addition, a fiber-fed bench spectrograph (PEPSI) capable of
ultra high resolution spectroscopy and spectropolarimetry (R = 40,000-300,000) will be available as a principal
investigator instrument. The availability of all these instruments mounted simultaneously on the LBT permits
unique science, flexible scheduling, and improved operational support.
Instrumentation at Major Observatories II
Instrumentation at the Magellan Telescopes 2008
Show abstract
The Carnegie Institution operates the twin 6.5m Magellan Telescopes on behalf of the Magellan consortium (Carnegie
Institution of Washington, Harvard University, the University of Arizona, Massachusetts Institute of Technology, and the
University of Michigan). The two telescopes have been in routine operations at the Las Campanas Observatory since
2001 and 2002 respectively. We currently operate with a suite of instruments available at 6 active ports during regular
night-time science operations. Here, we briefly describe the capabilities, operation, and performance of the suite of
commissioned instruments including MagIC, PANIC, MIKE, MIKE-Fibers, LDSS3, IMACS, and MagE. Beyond the
instruments that are presently installed on site, we will also introduce the large number of instruments that are in
advanced stages of construction by teams throughout our consortium (FIRE, Four-Star, MegaCam, MMIRS, PFS,
PISCO, MIRAC4).
Comprehensive review of the converted MMT's instrument suite
Show abstract
The converted 6.5m MMT Observatory has a powerful suite of new instrumentation accumulated over the last eight
years. Pre-conversion instruments still in use at the f/9 Cassegrain focus are the facility Red and Blue Channel
spectrographs (R = 240 - 6600) and the visiting spectropolarimeter (SPOL). Instruments using the f/5 spectroscopic
configuration are the bench mounted 300-fiber spectrographs Hectospec (R=1000) and Hectochelle (R=30,000), and the
single slit, cross-dispersed spectrograph MAESTRO (R=28,000 - 93,000). The f/5 imaging configuration offers
Megacam, a 24' x 24' CCD mosaic camera and SWIRC, a YJH NIR imager. The MMT's pioneering f/15 adaptive
secondary mirror enables high-resolution imaging and spectroscopy in the infrared with the ARIES, CLIO, PISCES and
BLINC/MIRAC instruments. The AO system will shortly be significantly enhanced with the addition of a Rayleigh laser
guide star system which is currently being commissioned. Upcoming instrumentation will include slit mask
spectrographs in the infrared (MMIRS) and optical (BINOSPEC). This review paper presents all the available
instruments capabilities and demonstrates how the observatory has become highly efficient at managing multiple
secondary mirrors and a large instrument suite.
Optical Imaging
The LSST camera overview: design and performance
Show abstract
The LSST camera is a wide-field optical (0.35-1μm) imager designed to provide a 3.5 degree FOV with 0.2
arcsecond/pixel sampling. The detector format will be a circular mosaic providing approximately 3.2 Gigapixels per
image. The camera includes a filter mechanism and shuttering capability. It is positioned in the middle of the telescope
where cross-sectional area is constrained by optical vignetting and where heat dissipation must be controlled to limit
thermal gradients in the optical beam. The fast f/1.2 beam will require tight tolerances on the focal plane mechanical
assembly. The focal plane array operates at a temperature of approximately -100°C to achieve desired detector performance. The
focal plane array is contained within a cryostat which incorporates detector front-end electronics and thermal control.
The cryostat lens serves as an entrance window and vacuum seal for the cryostat. Similarly, the camera body lens serves
as an entrance window and gas seal for the camera housing, which is filled with a suitable gas to provide the operating
environment for the shutter and filter change mechanisms. The filter carousel accommodates 5 filters, each 75 cm in diameter, for rapid exchange without external intervention.
The Pan-STARRS Gigapixel Camera #1 and STARGRASP controller results and performance
Show abstract
The Pan-STARRS project has completed its first 1.4 gigapixel mosaic focal plane CCD camera, Gigapixel Camera #1
(GPC1). The mosaic focal plane of 60 densely packed 4k×4k MITLL CCD Orthogonal Transfer Arrays (OTAs)
constitutes the World's largest CCD camera. The camera represents an extremely cost and time efficient effort with a
less than 18 month production and integration phase and an approximate cost of $4 million USD (excluding NRE). The
controller electronics named STARGRASP was developed to handle the 480 outputs at near 1Mpixel/sec rates with
Gigabit Ethernet interfaces and can be scaled to even larger focal planes. Sophisticated functionality was developed for
guide readout and on-detector tip-tilt image compensation with selectable region logic for standby or active operation,
high output count, close four side buttable packaging and deep depletion construction. We will discuss the performance
achieved, on-sky results, design, tools developed, shortcomings and future plans.
The Dark Energy Camera (DECam)
Show abstract
We describe the Dark Energy Camera (DECam), which will be the primary instrument used in the Dark Energy Survey.
DECam will be a 3 sq. deg. mosaic camera mounted at the prime focus of the Blanco 4m telescope at the Cerro-Tololo
International Observatory (CTIO). DECam includes a large mosaic CCD focal plane, a five element optical corrector,
five filters (g,r,i,z,Y), and the associated infrastructure for operation in the prime focus cage. The focal plane consists of
62 2K x 4K CCD modules (0.27"/pixel) arranged in a hexagon inscribed within the roughly 2.2 degree diameter field of
view. The CCDs will be 250 micron thick fully-depleted CCDs that have been developed at the Lawrence Berkeley
National Laboratory (LBNL). Production of the CCDs and fabrication of the optics, mechanical structure, mechanisms,
and control system for DECam are underway; delivery of the instrument to CTIO is scheduled for 2010.
First light of UT 15-band dichroic-mirror camera
Mamoru Doi,
Junji Hayano,
Hiroyuki Utsunomiya,
et al.
Show abstract
A dichroic mirror/filter can divide light into two different wavelength bands by the principle of interference. We proposed to use more than a dozen of these mirrors, and make a simultaneous imager in many color bands. This also enables us to make a powerful spectrograph which uses many CCDs. We here report the first light of UT 15-band Dichroic-Mirror Camera. We successfully obtained the first light at the Cassegrain focus of the 1.5-m Kanata telescope in May 2007. We also carried out the second observing run in March 2008. Our instrument covers a wide wavelength range (390-930nm), and the field of view is about 4.5 arcmin in diameter with 0.27arcsec/pixel. Image quality was limited by seeing (~1.2 arcsec at best). We describe basic design, characteristics, and performance of our instrument as well as early observational results. Future prospect of dichroic mirrors instruments will also be briefly discussed.
Optical Spectroscopy
WIYN bench upgrade: a revitalized spectrograph
Show abstract
We describe the redesign and upgrade of the versatile fiber-fed Bench Spectrograph on the WIYN 3.5m telescope. The
spectrograph is fed by either the Hydra multi-object positioner or integral-field units (IFUs) at two other ports, and can
be configured with an adjustable camera-collimator angle to use low-order and echelle gratings. The upgrade, including
a new collimator, charge-coupled device (CCD) and modern controller, and volume-phase holographic gratings
(VPHG), has high performance-to-cost ratio by combining new technology with a system reconfiguration that optimizes
throughput while utilizing as much of the existing instrument as possible. A faster, all-refractive collimator enhances
throughput by 60%, nearly eliminates the slit-function due to vignetting, and improves image quality to maintain
instrumental resolution. Two VPH gratings deliver twice the diffraction efficiency of existing surface-relief gratings: A
740 l/mm grating (float-glass and post-polished) used in 1st and 2nd-order, and a large 3300 l/mm grating (spectral
resolution comparable to the R2 echelle). The combination of collimator, high-quantum efficiency (QE) CCD, and VPH
gratings yields throughput gain-factors of up to 3.5.
A spatial heterodyne spectrometer for diffuse H-alpha spectroscopy
Show abstract
The University of Wisconsin Astronomy Department and the Space Astronomy Lab at UW are designing
an SHS spectrometer for the WIYN 3.5-meter telescope on Kitt Peak and the SALT 10-meter telescope in
South Africa. The new device will be mated to the Sparsepak, (Bershady et al, 2004, 2005) and/or the
Hydra fiber array at WIYN, and fed by either the prime focus image at SALT or the High Resolution
Spectrograph fiber-feed at SALT. The spectrograph will produce spectra at a reciprocal dispersion, R =
25,000 in 20 orders, each order covering an average wavelength band 250 km/s wide, for a total
wavelength range of 5000 km/s. Spectra from approximately 82 fibers will be resolved. Once the system is
proven at WIYN, and because the aperture size for this spectrometer does not scale with telescope size, we
will be able to test this same prototype at the SALT 10-meter telescope. This will be the first application of
this technique to large aperture astronomical observations.
The SOPHIE spectrograph: design and technical key-points for high throughput and high stability
Show abstract
SOPHIE is a new fiber-fed echelle spectrograph in operation since October 2006 at the 1.93-m telescope of Observatoire
de Haute-Provence. Benefiting from experience acquired on HARPS (3.6-m ESO), SOPHIE was designed to obtain
accurate radial velocities (~3 m/s over several months) with much higher optical throughput than ELODIE (by a factor of
10). These enhanced capabilities have actually been achieved and have proved invaluable in asteroseismology and
exoplanetology. We present here the optical concept, a double-pass Schmidt echelle spectrograph associated with a high
efficiency coupling fiber system, and including simultaneous wavelength calibration. Stability of the projected spectrum
has been obtained by the encapsulation of the dispersive components in a constant pressure tank. The main
characteristics of the instrument are described. We also give some technical details used in reaching this high level of
performance.
The optical design of the Southern African Large Telescope high resolution spectrograph: SALT HRS
Show abstract
SALT HRS is a fiber-fed cross-dispersed echelle spectrograph designed for high resolution and high efficiency seeing-limited
spectroscopy on the Southern African Large Telescope. The spectrograph, which has a dual channel white
pupil design, uses a single R4 echelle grating, a dichroic beam-splitter, and volume phase holographic gratings
as cross-dispersers. The echelle grating has 41.6 grooves/mm and is illuminated with a 200mm diameter beam.
This allows R = 16,000 with a 2.2" fiber and complete wavelength coverage from 370 nm to 890 nm. Resolving
powers of R ≈ 37,000 and 67,000 are obtained using image slicers. The dichroic beam-splitter is used to split the
wavelength coverage between two fully dioptric cameras. The white pupil transfer optics are used to demagnify
the pupil to 111mm which ensures that the camera dimensions are kept reasonable whilst also allowing the
efficient use of VPH gratings. The spectrograph optics are enclosed inside a vacuum tank to ensure immunity to
atmospheric pressure and temperature changes. The entire spectrograph is mechanically and thermally insulated.
Construction of SALT HRS began at Durham University's Centre for Advanced Instrumentation in August 2007
and is expected to be complete in 2009. The spectrograph optical design is largely based on work completed at
the University of Canterbury's Department of Physics and Astronomy.
SixPak: a wide-field IFU for the William Herschel Telescope
Show abstract
We intend to construct SixPak, a wide-field fibre-based IFU for the 4.2-meter William Herschel Telescope on La Palma.
The fibre bundle will consist of 238 fibres, each 3.0 arcsec in diameter, piping light from the Nasmyth focal plane of the
WHT to the existing WYFFOS bench spectrograph. A total of 217 fibres will be densely packed to span a hexagonal
field of view of 64 × 55 arcsec. The remaining 21 fibres will collect light from the sky background. SixPak is optimized
for 2-dimensional spectroscopy at intermediate resolutions of extended objects of low surface brightness. At Nasmyth
focus, a focal reducer matches the f-ratio of the telescope (f/11) to the "optimal" f-ratio of the fibres (f/3) to reduce the
losses due to focal ratio degradation in the fibres. Microlenses convert the output f-ratio of the fibres to the f-ratio of the
WYFFOS collimator (f/8.2). By means of an exchangeable slit at the pupils of the microlenses, a spectral resolution of R
= 10,000 can be achieved. The intention is that SixPak will be open for general use in order to allow easy access to the
broadest possible astronomical community.
New design approaches for a very high resolution spectrograph for the combined focus of the VLT
Show abstract
To achieve very-high spectral resolutions (R>100,000) with large telescopes (D>8m) new optical solutions have been
investigated in the context of the ESPRESSO project for the VLT, starting from the initial design of CODEX for the E-ELT.
ESPRESSO is a high-efficiency, high-stability, high-resolution visible spectrograph for the combined Coude focus
of the VLT. Among these new solutions, we can mention: free-form optics, used to design an all-mirror anamorphic
pupil slicer, large mosaic echelle grating, slanted VPH gratings, super-corrected atmospheric dispersion corrector. All
these solutions have been usefully applied to design the spectrograph for ESPRESSO, and its Coude relay system.
PEPSI: the Potsdam Echelle Polarimetric and Spectroscopic Instrument for the LBT
Show abstract
We present the status of PEPSI, the bench-mounted fibre-fed and stabilized "Potsdam Echelle Polarimetric and
Spectroscopic Instrument" for the 2×8.4m Large Binocular Telescope in southern Arizona. PEPSI is under construction
at AIP and is scheduled for first light in 2009/10. Its ultra-high-resolution mode will deliver an unprecedented spectral
resolution of approximately R=310,000 at high efficiency throughout the entire optical/red wavelength range 390-1050nm without the need for adaptive optics. Besides its polarimetric Stokes IQUV mode, the capability to cover the
entire optical range in three exposures at resolutions of 40,000, 130,000 and 310,000 will surpass all existing facilities in
terms of light-gathering-power times spectral-coverage product. A solar feed will make use of the spectrograph also
during day time. As such, we hope that PEPSI will be the most powerful spectrometer of its kind for the years to come.
The upgrade of HARPS to a full-Stokes high-resolution spectropolarimeter
Show abstract
We present the design of a compact module that converts the HARPS instrument at the 3.6-m telescope at
La Silla to a full-Stokes high-resolution spectropolarimeter. The polarimeter will replace the obsolete Iodine
cell inside the HARPS Cassegrain adapter. Utilizing the two fibers going into the spectrograph, two dual-beam
systems can be positioned in the beam: one with a rotating superachromatic quarter-wave plate for circular
polarimetry and one with a rotating superachromatic half-wave plate for linear polarimetry. A large polarimetric
precision is ensured by the beam-exchange technique and a minimal amount of instrumental polarization. The
polarimeter, in combination with the ultra-precise HARPS spectrograph, enables unprecedented observations of
stellar magnetic fields and circumstellar material without compromising the successful planet-finding program.
The spectrograph ESOPO: scientific goals, high-level requirements, and introduction to the design
J. Echevarría,
A. Farah,
R. Costero,
et al.
Show abstract
In this paper we present the Medium Resolution Spectrograph ESOPO, an instrument designed and built for the 2.1m
Telescope at the Observatorio Astronómico Nacional at San Pedro Mártir. We discuss the Scientific Goals and the High
Level Requirements necessary to translate these goals to optical, mechanical and control specifications. We make an
introduction to its conceptual dual-arm design. The optical design is based on a non-classical configuration. The gratings
are illuminated in a conical mode working in a quasi Littrow configuration which has the advantage of optimizing the
efficiency and the pupil area on the grating. We show here the results of an experimental evaluation of the concept. The
optical design, mechanical structure, slit-mask and acquisition system, control systems, and a study of thermal
compensators, are discussed briefly, references to more extended contributions in these proceedings are made. The
management schematics of the project are briefly discussed.
Infrared Cameras and Spectrometers
Performance of HAWK-I: the new high acuity wide-field K-band imager
Show abstract
HAWK-I is the newly commissioned High Acuity Wide-field K-band Imager at the ESO Very Large Telescope. It is a
0.9-2.5 micron imager with a field of view of 7.5×7.5 arcmin sampled at 106 mas with four Hawaii2RG detectors. It has
a full reflective design that was optimised for image quality and throughput.We present an overview of its performance as
measured during the commissioning and first science runs. In particular, we describe a detector read-out mode that allows
us to increase the useful dynamic range of the detector, and a distortion calibration resulting in <5mas relative astrometry
across the field.
Day-one science with CanariCam, the Gran Telescopio Canarias multi-mode mid-infrared camera
Show abstract
CanariCam is the facility multi-mode mid-IR camera developed by the University of Florida for the 10-meter Gran
Telescopio Canarias (GTC) on La Palma. CanariCam has four science modes that provide the GTC community with an
especially powerful research tool for imaging, grating spectroscopy, coronagraphy, and dual-beam polarimetry.
Instrument commissioning in the laboratory at the University of Florida indicates that all modes perform as required, and
the next step is on-telescope commissioning. After commenting on the instrument status, we will review key features of
each of these science modes, with emphasis on illustrating each mode with science examples that put the system
performance, particularly the anticipated sensitivity, into perspective.
FMOS: the fiber multiple-object spectrograph: Part VI. Onboard performances and results of the engineering observations
Show abstract
FMOS: the Fiber Multiple-Object Spectrograph is the next common-use instrument of the Subaru Telescope,
having a capability of 400 targets multiplicity in the near-infrared 0.9-1.8μm wavelength range with a field
coverage of 30' diameter. FMOS consists of three units: 1) the prime focus unit including the corrector lenses,
the Echidna fiber positioner, and the instrument-bay to adjust the instrument focus and shift the axis of the
corrector lens system, 2) the fiber bundle unit equipping two fiber slits on one end and a fiber connector box with
the back-illumination mechanism on the other end on the bundle, 3) the two infrared spectrographs (IRS1 and
IRS2) to obtain 2×200 spectra simultaneously. After all the components were installed in the telescope at the
end of 2007, the total performance was checked through various tests and engineering observations. We report
the results of these tests and demonstrate the performance of FMOS.
FIRE: a near-infrared cross-dispersed echellette spectrometer for the Magellan telescopes
Show abstract
FIRE (the Folded-port InfraRed Echellette) is a prism cross-dispersed infrared spectrometer, designed to deliver singleobject
R=6000 spectra over the 0.8-2.5 micron range, simultaneously. It will be installed at one of the auxiliary
Nasmyth foci of the Magellan 6.5-meter telescopes. FIRE employs a network of ZnSe and Infrasil prisms, coupled with
an R1 reflection grating, to image 21 diffraction orders onto a 2048 × 2048, HAWAII-2RG focal plane array.
Optionally, a user-controlled turret may be rotated to replace the reflection grating with a mirror, resulting in a singleorder,
longslit spectrum with R ~ 1000. A separate, cold infrared sensor will be used for object acquisition and guiding.
Both detectors will be controlled by cryogenically mounted SIDECAR ASICs. The availability of low-noise detectors
motivates our choice of spectral resolution, which was expressly optimized for Magellan by balancing the scientific
demand for increased R with practical limits on exposure times (taking into account statistics on seeing conditions).
This contribution describes that analysis, as well as FIRE's optical and opto-mechanical design, and the design and
implementation of cryogenic mechanisms. Finally, we will discuss our data-flow model, and outline strategies we are
putting in place to facilitate data reduction and analysis.
FLAMINGOS-2: the facility near-infrared wide-field imager and multi-object spectrograph for Gemini
Show abstract
We report on the design and status of the FLAMINGOS-2 instrument - a fully-cryogenic facility near-infrared imager
and multi-object spectrograph for the Gemini 8-meter telescopes. FLAMINGOS-2 has a refractive all-spherical optical
system providing 0.18-arcsecond pixels and a 6.2-arcminute circular field-of-view on a 2048×2048-pixel HAWAII-2
0.9-2.4 μm detector array. A slit/decker wheel mechanism allows the selection of up to 9 multi-object laser-machined
plates or 3 long slits for spectroscopy over a 6×2-arcminute field of view, and selectable grisms provide resolutions from
~1300 to ~3000 over the entire spectrograph bandpass. FLAMINGOS-2 is also compatible with the Gemini Multi-
Conjugate Adaptive Optics system, providing multi-object spectroscopic capabilities over a 3×1-arcminute field with
high spatial resolution (0.09-arcsec/pixel). We review the designs of optical, mechanical, electronics, software, and On-
Instrument WaveFront Sensor subsystems. We also present the current status of the project and future plans, including
on-sky delivery planned for late 2008.
CRIRES: commissioning and first science results
Show abstract
CRIRES is a cryogenic, pre-dispersed, infrared Echelle spectrograph designed to provide a nominal resolving
power ν/Δν of 105 between 1000 and 5000 nm for a nominal slit width of 0.2". The CRIRES installation at
the Nasmyth focus A of the 8-m VLT UT1 (Antu) marks the completion of the original instrumentation plan
for the VLT. A curvature sensing adaptive optics system feed is used to minimize slit losses and to provide 0.2"
spatial resolution along the slit. A mosaic of four Aladdin InSb-arrays packaged on custom-fabricated ceramic
boards has been developed. It provides for an effective 4096 × 512 pixel focal plane array to maximize the free
spectral range covered in each exposure. Insertion of gas cells is possible in order to measure radial velocities with
high precision. Measurement of circular and linear polarization in Zeeman sensitive lines for magnetic Doppler
imaging is foreseen but not yet fully implemented. A cryogenic Wollaston prism on a kinematic mount is already
incorporated. The retarder devices will be located close to the Unit Telescope focal plane. Here we briefly recall
the major design features of CRIRES and describe the commissioning of the instrument including a report of
extensive testing and a preview of astronomical results.
The performance of TripleSpec at Palomar
Show abstract
We report the performance of Triplespec from commissioning observations on the 200-inch Hale Telescope
at Palomar Observatory. Triplespec is one of a set of three near-infrared, cross-dispersed spectrographs
covering wavelengths from 1 - 2.4 microns simultaneously at a resolution of ~2700. At Palomar, Triplespec
uses a 1×30 arcsecond slit. Triplespec will be used for a variety of scientific observations, including
moderate to high redshift galaxies, star formation, and low mass stars and brown dwarfs. When used in
conjunction with an externally dispersed interferometer, Triplespec will also detect and characterize
extrasolar planets.
Precision radial velocity spectrograph
Show abstract
We present a conceptual design for a Precision Radial Velocity Spectrograph (PRVS) for the Gemini telescope. PRVS is
a fibre fed high resolving power (R~70,000 at 2.5 pixel sampling) cryogenic echelle spectrograph operating in the near
infrared (0.95 - 1.8 microns) and is designed to provide 1 m/s radial velocity measurements. We identify the various
error sources to overcome in order to the required stability. We have constructed models simulating likely candidates
and demonstrated the ability to recover exoplanetary RV signals in the infrared. PRVS should achieve a total RV error of
around 1 m/s on a typical M6V star. We use these results as an input to a simulated 5-year survey of nearby M stars.
Based on a scaling of optical results, such a survey has the sensitivity to detect several terrestrial mass planets in the
habitable zone around nearby stars. PRVS will thus test theoretical planet formation models, which predict an abundance
of terrestrial-mass planets around low-mass stars.We have conducted limited experiments with a brass-board instrument
on the Sun in the infrared to explore real-world issues achieving better than 10 m/s precision in single 10 s exposures and
better than 5 m/s when integrated across a minute of observing.
Airborne Instruments
Verification of the optical system performance of FIFI-LS: the field-imaging far-infrared line spectrometer for SOFIA
Show abstract
FIFI-LS is a Field-Imaging Line Spectrometer designed for the SOFIA airborne observatory. The instrument will
operate in the far infrared (FIR) wavelength range from 42 to 210 μm. Two spectrometers operating between
42-110 μm and 110-210 μm allow simultaneous and independent diffraction limited 3D imaging over a field of
view of 6" × 6" and 12" × 12" respectively. We have developed a telescope simulator to test the imaging and
spectral performance of FIFI-LS in the FIR. Here, we present the telescope simulator as well as the performance
verification of FIFI-LS using the simulator. Finally we compare the measurements with the theoretical expected
performance of FIFI-LS.
GREAT: a first light instrument for SOFIA
Show abstract
GREAT (German REceiver for Astronomy at Terahertz frequencies) has been selected as first-light instrument for the
early science flights of SOFIA, scheduled for early 2009. In its first-light configuration GREAT will allow observations
in two out of three FIR bands: two low frequency channels 1.25-1.5 THz and 1.82-1.92 THz for observations of, e.g.,
highly excited CO and of ionized carbon, and a 2.7 THz channel focusing on the ground-state transition of deuterated
molecular hydrogen HD. A forth channel, centered on the 4.7 THz transition of atomic oxygen will become available
later.
The observatory schedule asks for delivery of the instrument in early 2009. At the time of the conference system level
assembly, integration, and verification (AIV) is ongoing, and we report on the performance of the integrated system.
Shipment to NASA/DAOF (Dryden aircraft operations facility) in Palmdale/California for aircraft integration is currently
planned for mid December 2008.
Ground-based commissioning of FLITECAM
Show abstract
FLITECAM is a 1-5 micron spectrometer and camera developed at UCLA for NASA's Stratospheric Observatory for
Infrared Astronomy (SOFIA). On SOFIA, FLITECAM will take advantage of lower backgrounds from 3-5 microns and
will provide access to spectral regions completely or partially absorbed by water vapor at even the best ground-based
sites. FLITECAM employs large cryogenic optics and an ALADDIN III 1024 × 1024 InSb detector to inscribe an 8
arcminute field of view with 0.48 arcsec/pixel spatial resolution. The optical components are cooled with liquid nitrogen
and a liquid helium reservoir is used to establish an operational temperature of 30 K for the InSb array. FLITECAM has
two primary observing modes, imaging and spectroscopy. A pupil-viewing mode, for examination of the primary mirror
surface, and a high-speed snapshot mode for occultation observations are also provided. Ground-based commissioning
of the instrument using the Shane 3-meter telescope at UCO/Lick Observatory has been completed successfully. In
addition to broad-band filters, the imaging mode accommodates several narrow-band filters. A data reduction pipeline
processes dithered image sets in real-time during the flight. The grism spectroscopy mode employs three direct-ruled
KRS-5 grisms and fixed slits of either 1" × 60" or 2 × 60" to yield resolving powers (FWHM) of R~1700 and 900
respectively. Observations are scripted using AORs (Astronomical Observation Requests) in both modes. A pilot survey
of 3.3 micron emission in planetary nebulae performed with FLITECAM at UCO/Lick Observatory demonstrates the
potential of the grism mode.
Improved sensitivity of the SOFIA target acquisition and tracking cameras and a high speed diagnostics camera for telescope movements in flight
Show abstract
The telescope of the Stratospheric Observatory for Infrared Astronomy (SOFIA) uses three CCD based visible light
cameras for target acquisition and tracking. All three cameras use the TH7888A CCD chips which are quite suitable in
terms of their geometry and readout speed. However, their quantum efficiency and dark current are not comparable to
newer high-sensitivity CCD chips now widely used in astronomy. The Deutsche SOFIA Institute (DSI) under contract of
the German Aerospace Center (DLR) has therefore initiated an upgrade project of the cameras with back-illuminated,
high-sensitivity and low dark current CCD chips, e2v 47-20. The expected improvements in sensitivity range between
1.2 and 2.5 stellar magnitudes for the three cameras. In addition, DSI and DLR plan to provide a high-speed camera
which can monitor stellar images of the SOFIA main telescope in the visible spectral range at frame rates of up to ~ 300
frames per second. Analysis of image movements at such speeds will help to identify sources of instabilities in flight,
such as vibrations and wind loads. Knowledge of such disturbances and their influence on the telescope system will be
essential to achieve the requirement of 0.6 arc-seconds (rms) pointing stability.
Solar Instruments
ChroTel: a robotic telescope to observe the chromosphere of the Sun
Show abstract
The Chromospheric Telescope (ChroTel) is a 10 cm robotic telescope to observe the full solar disk with a 2k × 2k CCD
at high temporal cadence. It is located at the Observatorio del Teide, Tenerife, Spain, next to the 70 cm German Vacuum
Tower Telescope (VTT). ChroTel contains a turret system that relays a stabilized image of the solar disk into a
laboratory within the VTT building. The control design allows a fully robotic operation. Observations are carried out in
three chromospheric wavelengths (CaK: 393 nm, Ha: 652 nm, HeI 1083 nm).
Combination of two Fabry-Pérot etalons and a grating spectrograph for imaging polarimetry of the Sun
Show abstract
Imaging spectroscopy of the Sun is a challenging task usually performed with Fabry-Perot etalons. The common setup is a combination of two or three etalons in series and a narrow-band prefilter. The requirement of one, usually expensive prefilter for every desired wavelength limits the number of spectral regions that can be observed.
We present a novel instrument combination consisting of two Fabry-Perot etalons and a grating spectrograph, which allows for observations in any wavelength between 390 nm and 660 nm without the need for narrow-band prefilters. Furthermore, two or more adjacent monochromatic images are projected on the detector, each image corresponding to a different spectral transmission peak of the Fabry-Perot filtergraph. Together with our Zurich Imaging Polarimeter (ZIMPOL) the system is installed at the telescope of the Istituto Ricerche Solari Locarno (IRSOL) where it will be used for two-dimensional spectropolarimetry. We present a description of the instrument and test observations.
Apodized apertures for solar coronagraphy
Show abstract
An apodized aperture should make it possible to observe the solar corona without the need of a Lyot coronagraph. We
show in this communication that Sonine functions are much better apodizers for the observation of the solar corona than
the generalized prolate spheroidal functions previously proposed. For a perfect circular aperture of diameter unity operated
in space, a simple Sonine apodization of the form (1 - 4r2), with |r| ≤ 1/2 should sufficiently reduce the diffraction halo
produced by the solar disc to observe the corona very close to the solar limb (a few arcsec). The throughput is just one
third of the clear aperture.
A new spectro-polarimeter for solar prominence and filament magnetic field measurements
Show abstract
We are constructing a spectro-polarimeter using the 40-cm coronagraph at the Evans Solar Facility of the National
Solar Observatory in Sunspot, NM for the purpose of measuring the vector magnetic field in prominences and
filaments. The Prominence Magnetometer (ProMag) is comprised of a polarization modulation package and a
spectrograph. The modulation optics are located at the prime focus of the coronagraph along with calibration
optics and a beamsplitter that creates two beams of orthogonal Stokes states. The spectrograph resides at the
coude focus of the coronagraph. The polarizations of the two chromospheric lines of neutral helium, at 587.6 nm
and 1083.0 nm, are to be observed simultaneously. We present details of the design of the spectro-polarimeter.
Polarization effects in Fabry-Pérot interferometer-based solar spectrometers
Show abstract
The influence of thin film multilayer coatings of Fabry-Perot interferometers (FPI) on polarimetric measurements
is investigated. Because the oblique ray reflectivity of the coatings in general is polarization dependent, the
transmission profile is slightly different for the s- and p-components of light passing through the FPI, resulting
in weak artificial polarization signals. The difference increases with larger angles of incidence and higher design
reflectivity of the coatings. In order to estimate the magnitude of the effect, we perform numerical calculations
with different coating designs and different optical configurations. We conclude that while current slow focal ratio
solar FPI spectrometers are safe, high-precision polarimetric measurements with large aperture solar telescopes
which may require considerably steeper focal ratios may suffer from spurious polarization effects.
Adaptive Optics Fed Instrumentation and High Contrast Imaging I
SPHERE: a planet finder instrument for the VLT
Show abstract
Direct detection and spectral characterization of extra-solar planets is one of the most exciting but also one of the most
challenging areas in modern astronomy. The challenge consists in the very large contrast between the host star and the
planet, larger than 12.5 magnitudes at very small angular separations, typically inside the seeing halo. The whole design
of a "Planet Finder" instrument is therefore optimized towards reaching the highest contrast in a limited field of view and
at short distances from the central star. Both evolved and young planetary systems can be detected, respectively through
their reflected light and through the intrinsic planet emission. We present the science objectives, conceptual design and
expected performance of the SPHERE instrument.
HiCIAO: the Subaru Telescope's new high-contrast coronographic imager for adaptive optics
Show abstract
The High-Contrast Coronographic Imager for Adaptive Optics (HiCIAO), is a coronographic simultaneous differential
imager for the new 188-actuator AO system at the Subaru Telescope Nasmyth focus. It is designed primarily to search
for faint companions, brown dwarves and young giant planets around nearby stars, but will also allow observations of
disks around young stars and of emission line regions near other bright central sources. HiCIAO will work in
conjunction with the new Subaru Telescope 188-actuator adaptive optics system. It is designed as a flexible,
experimental instrument that will grow from the initial, simple coronographic system into more complex, innovative
optics as these technologies become available. The main component of HiCIAO is an infrared camera optimized for
spectral simultaneous differential imaging that uses a Teledyne 2.5 μm HAWAII-2RG detector array operated by a
Sidecar ASIC. This paper reports on the assembly, testing, and "first light" observations at the Subaru Telescope.
LINC-NIRVANA: achieving 10 mas imagery on the Large Binocular Telescope
Show abstract
LINC-NIRVANA is an innovative imaging interferometer fed by dedicated multi-conjugated adaptive optics systems.
The instrument combines the light of the two, 8.4-meter primary mirrors of the Large Binocular Telescope (LBT) on a
single focal plane, providing panoramic imagery with 23-meter spatial resolution. The instrument employs a number of
innovative technologies, including multi-conjugated adaptive optics, state-of-the-art materials, low vibration mechanical
coolers, active and passive control, and sophisticated software for data analysis. LINC-NIRVANA is entering its final
integration phase, with the large adaptive-optics and imaging subsystems coming together in the clean room in
Heidelberg. Here, we report on progress, including insights gained on integration of large instruments.
Conceptual design of IR multi-IFU spectrograph with MOAO
Show abstract
To study properties of cold dark matter (CDM), which can only be observed through its gravitational interaction
with galaxies, spatially resolved spectra at least to the K-band are desirable. We started designing a spectrograph
which observes multiple targets spatially resolved in a telescope field of view fed with multi-object adaptive
optics (MOAO). The current design either places field lenses on the telescope field of view to image the pupil
onto steering mirrors, or uses a single set of field lens to deliver beams to pick-off arms. The steering mirror on
the pupil image tilts and selects a sub-field from each of the telescope field of view physically split by the field
lenses. This allows cheaper and more robust construction of a method to select the target fields with a limitation
in selections of the target fields. On the other hand, the pick-off arm implementation allows more flexibility
in assigning targets to fields of the integral field units (IFUs) especially when targets are clustered. The IFU
arranges spatial elements of each of sub-field of view to be fed into the spectrograph. If enough pixels are afforded,
using microlens arrays, which image pupils of spatial elements onto the object plane of the spectrograph is ideal
in robustness. Otherwise, an image slicer is to be located to arrange the sub-field of view onto the entrance slit.
The instrument should be built as modules to allow expeditious scientific results.
Diffraction limited imaging in the visible from large ground-based telescopes: new methods for future instruments and telescopes
Show abstract
Faint object diffraction limited imaging in the visible from the ground has recently been demonstrated on a 5 m
telescope with more than twice the resolution of Hubble for the first time. It has shown the way towards diffraction
limited imaging in the visible with the next generation of large telescopes. This paper describes the results of
experiments to show how this is achieved and what is needed to work well with faint natural guide stars. The
importance of a large isoplanatic patch size is also emphasised. In particular, we will describe a new approach to the
design of high efficiency, low order adaptive curvature sensors which use photon counting CCD detectors. Such
systems used on larger telescopes together with image segmentation and resynthesis techniques using closure phase
techniques are shown to have an important place in achieving these goals. The optimum combination of these different
techniques will be explained for a variety of different applications.
Instruments for ELTs I
Early light TMT instrumentation
Show abstract
The Thirty Meter Telescope (TMT) project will provide diffraction limited and seeing limited capabilities that will be
highly synergistic with JWST and other planned astronomy missions. TMT will thus be poised to tackle most of the
questions confronting scientists today and for the next several decades. The early light instrumentation will provide NIR
imaging and integral field spectroscopy designed to sample even the tiny 7mas images provided at 1.2 microns by a
multi-conjugate laser guide star AO system, near-infrared multi-slit spectroscopy over a 2 arcmin field (fed by the same
AO system, tuned for wide field performance), and wide field multi-object spectroscopy in the 0.3 - 1 micron
wavelength region. TMT is being designed, as a system, to take advantage of the observational opportunities that a
diffraction limited 30m telescope will afford. Results of detailed end-to-end modeling demonstrate excellent
performance in both seeing-limited and diffraction-limited modes. TMT is also being designed to operate in a very
efficient manner. Details of how this will be accomplished, descriptions of the planned instrumentation with focus on the
early light instruments, new technologies that will be implemented, and a summary of the anticipated observing
programs and how these will complement observations from other facilities are described.
Studies for the first generation of instruments for the European ELT
Show abstract
The European Southern Observatory (ESO) is conducting a phase B study of a European Extremely Large Telescope (E-ELT).
The baseline concept foresees a 42m primary, 5 mirror adaptive telescope with two of the mirrors giving the
possibility of very fast correction of the atmospheric turbulence. In parallel to the telescope study, ESO is coordinating
8 studies of instruments and 2 of post-focus Adaptive Optics systems, carried out in collaboration with Institutes in the
member states. Scope of the studies, to be completed by 1Q 2010, is to demonstrate that the high priority scientific goals of
the E-ELT project can be achieved with feasible and affordable instruments. The main observing modes being considered
are: NIR wide field imaging and spectroscopy to the diffraction limit or with partial correction of the atmospheric seeing;
high spectral resolution, high stability visible spectroscopy; high contrast, diffraction limited imaging and spectroscopy; DL
mid-infrared imaging and spectroscopy. The status of the 8 current studies is presented.
Making instruments work on the European ELT
Show abstract
The title of this paper was chosen to highlight the fact that the installation and operation of instrumentation on Extremely
Large Telescopes (ELTs) will not be entirely simple or straightforward. The cost of construction and operation of ELTs
will be such that substantial pressures will develop for proportional increases in the level of performance of the
instrumentation, using as much of the electromagnetic information arriving at the focal plane as possible. This in turn
will require complex instruments using adaptive optics, multiple channels or highly spatially multiplexed instruments. In
the case of the European ELT, it will be a facility much in demand by ESOs 4000+ community of astronomers. The
instrument infrastructure must therefore be able to accommodate the full range of projects likely to be undertaken. In this
paper, we will discuss the instrument interfaces and infrastructure as envisioned in the current baseline for the European
ELT and the requirements underpinning them.
An optical design for a wide-field optical spectrograph for TMT
Show abstract
We describe a preliminary optical design for a multi-object, wide-field, optical echellette spectrograph that is intended to
serve a broad range of science. It will produce low-resolution, single-order spectra for survey-mode programs targeting
as many objects as possible and also moderate-resolution, multiple-order spectra for a reduced number of targets. The
design uses all refracting optics. The first optical element of the spectrograph is a wide-field corrector for the telescope
that causes the chief rays to be perpendicular to the focal plane. The collimator, which has been designed on-axis, can
then be duplicated to target multiple, off-axis fields in a multiple-barrel configuration. The collimator optics include an
achromatic field lens group that forms a sharp pupil over the full optical band-pass (320-1000 nm), followed by a
dichroic which splits the beam into a red and a blue channel. All remaining optical elements of the collimator, the
gratings, the cameras, and the detectors are then optimized for red or blue wavelengths. Both red and blue channels of
each beam of the spectrograph use reflection gratings to produce either a single-order spectrum at resolutions around
R=λ/Δλ=1000 or a five-order, R>5000 echellette spectrum with prism cross-dispersion. Both modes can target objects
anywhere in the collimated field of view. A direct imaging mode will also be provided.
Q-Spec: a concept for the Giant Magellan Telescope high resolution optical spectrograph
Show abstract
Q-Spec is a concept for the Giant Magellan Telescope High Resolution Optical Spectrograph. It is a seeing
limited, four channel spectrograph designed for high efficiency, high resolution spectroscopy from 305 to 1060 nm.
Overall instrument dimensions are minimized with anamorphic preslit optics, pupil slicing, and white pupil beam
demagnification. Q-spec uses two 300 × 1600mm R4 echelle grating mosaics of either 2 or 4 individual gratings,
with 41.6 and 31.6 grooves/mm line densities. Two beam sizes are selectable in the preslit optics. A 450mm beam
yields Rφ = 30,000 while a 900mm beam reaches Rφ = 60,000. Both beams are anamorphised before echelle
dispersion, and the larger beam is pupil sliced. The post-echelle white pupil transfer optics demagnify the beam
by 3. This allows the use of efficient vph grating cross-dispersers, and unvignetted f/1.5-2.0 dioptric cameras
with optical element diameters under 250 mm. The bandwidth is split by a dichroic prior to the entrance slit,
and by dichroics near the intermediate foci of the two sets of white pupil transfer optics. The four fixed spectral
formats have 2-pixel resolving powers of ~200,000 and it is anticipated that resolving powers of R = 150, 000 or
greater will be possible. The largest ccd is 6k × 6k with 15 μm pixels, and the minimum order separation is
around 10 arcseconds. Q-spec can be fed with fibers in either multiple-object and/or precision radial velocity
modes. Excluding the gravity-invariant thermal and vacuum enclosures, the instrument volume is a modest 5 × 2.5 × 2m in size.
CODEX: the high-resolution visual spectrograph for the E-ELT
Show abstract
A number of outstanding scientific problems require a high resolution, visual spectrograph at the E-ELT. Measuring the
dynamics of the universe, finding earth-like planets with radial velocity techniques, determining the chemical evolution
of the intergalactic medium and if physical constants varied in the past, all require a superior capability of measuring
exceedingly small Doppler shifts. We have started a Phase A study for CODEX at the E-ELT. We present here the
scientific cases, the requirements, the basic technical choices and trade offs, as well as a couple of design under
evaluation. We aim at a super stable instrument, capable of obtaining a radial velocity precision of 2 cm/sec over several
decades. It will be located at the coude focus. The design will make use of anamorphosis, pupil slicing, slanted VPH
gratings and a novel calibration system based on laser frequency combs. Several CODEX-related R&D activities are
running, and, in addition, a Call for Proposal for a precursor at the VLT has been issued.
System design and analysis of the exo-planet imaging camera and spectrograph (EPICS) for the European ELT
Show abstract
One of the main science objectives of the European ELT is the direct imaging of extrasolar planets. The large aperture of
the telescope has the potential to significantly enlarge the discovery space towards older gas giant exo-planets seen in
reflected light. In this paper, we give an overview of the EPICS system design strategy during the phase A study. In
order to tackle the critical limitations to high contrast, extensive end-to-end simulations will be developed since the start
to test different scenarios and guide the overall design.
Instruments for ELTs II
EAGLE: an MOAO fed multi-IFU in the NIR on the E-ELT
Show abstract
EAGLE is an instrument under conceptual study for the European Extremely Large Telescope (E-ELT). EAGLE will be
installed at the Gravity Invariant Focal Station of the E-ELT, covering a field of view between 5 and 10 arcminutes. Its
main scientific drivers are the physics and evolution of high-redshift galaxies, the detection and characterization of first-light
objects and the physics of galaxy evolution from stellar archaeology. The top level requirements of the instrument
call for 20 spectroscopic channels in the near infrared, assisted by Adaptive Optics. Several concepts of the Target
Acquisition sub-system have been studied and are briefly presented. Multi-Conjugate Adaptive Optics (MCAO) over a
segmented 5' field has been evaluated and compared to Multi-Object Adaptive Optics (MOAO). The latter has higher
performance and is easier to implement, and is therefore chosen as the baseline for EAGLE. The paper provides a status
report of the conceptual study, and indicates how the future steps will address the instrument development plan due to be
completed within a year.
Optical solutions for the multi-IFU instrument EAGLE for the European ELT
Show abstract
This paper summarizes the different optical concepts developed for the EAGLE Phase A design. EAGLE will be an
MOAO (Multi-object AO) IFU spectrometer operating between 0.8 and 2.5μm. The EAGLE consortium have
developed different concepts for the challenging problem of acquiring more than twenty objects in the patrol field of
view (FOV), correcting the wavefront along the line of sight to each of the objects and analyzing each object spatially
and spectrally with an Integral Field Spectrograph. The target selection FOV will be ≥20 square arcmin and the
individual target FOV can be selected to be either 1.65×1.65arcsec or 1.65×3.3arcsec. They will be sampled spatially at
75mas and with spectral resolutions of 4000 and 10000. Optical designs for target acquisition systems, integral-field
unit, and spectrographs have been developed. These will be compared and the expected performance will be described
in terms of the number of targets, overall patrol field of view, individual field of view, throughput, spectral resolving
power and image quality.
METIS: the mid-infrared E-ELT imager and spectrograph
Show abstract
METIS, the Mid-infrared ELT Imager and Spectrograph (formerly called MIDIR), is a proposed instrument for the
European Extremely Large Telescope (E-ELT), currently undergoing a phase-A study. The study is carried out within
the framework of the ESO-sponsored E-ELT instrumentation studies. METIS will be designed to cover the E-ELT
science needs at wavelengths longward of 3μm, where the thermal background requires different operating schemes. In
this paper we discuss the main science drivers from which the instrument baseline has been derived. Specific emphasis
has been given to observations that require very high spatial and spectral resolution, which can only be achieved with a
ground-based ELT. We also discuss the challenging aspects of background suppression techniques, adaptive optics in
the mid-IR, and telescope site considerations. The METIS instrument baseline includes imaging and spectroscopy at the
atmospheric L, M, and N bands with a possible extension to Q band imaging. Both coronagraphy and polarimetry are
also being considered. However, we note that the concept is still not yet fully consolidated. The METIS studies are
being performed by an international consortium with institutes from the Netherlands, Germany, France, United
Kingdom, and Belgium.
Instrumentation Techniques and Technologies I
High-resolution near-IR spectroscopy: from 4m to 40m class telescopes
E. Oliva,
L. Origlia
Show abstract
High resolution (HR) near infrared (NIR) spectroscopy is one of the youngest and less explored fields of astronomical
research. The few dedicated instruments which are presently available worldwide have remarkably
limited capabilities in terms of spectral coverage. In this paper we discuss some of the most important scientific
applications of HR-NIR spectroscopy and present the design of "SIMPLE", a simple (hence its name) and very
powerful instrument specifically designed for the E-ELT but which can be easily interfaced to existing 8-10 m
class telescopes. We also provide detailed information on the expected performances and limiting magnitudes of
SIMPLE on different telescopes.
The FIRST project: a single-mode fiber-based very high-dynamic range diffraction-limited imaging instrument at visible to near-infrared wavelengths
Show abstract
We describe the present status of the development of a very high-dynamic range, diffraction limited imaging instrument FIRST (Fibered Imager foR Single Telescope), among which goals is the detection of nearby extra-solar planets at visible to near-infrared wavelengths from the ground. We have started to develop a prototype system which consists of a number of novel designs such as a segmented micro mirror array and silicon micro machined single-mode fiber arrays. Furthermore, we have proposed to build a FIRST instrument for the CFHT, which will be complementary to high-dynamic range instruments developed for 8m class telescopes at near-infrared wavelengths.
Optimal fabrication of volume phase holographic grism with high efficiency and high dispersion, and its applications for astronomical observation
Show abstract
We had developed three types of large VPH grisms (110×106 mm2) for FOCAS of the 8.2 m Subaru Telescope with
high efficiency, high dispersion and small wavefront error in visible region. However, it has been highly difficult to
fabricate VPH gratings for longer wavelength due to thickness of the grating. In order to overcome this problem, by
optimizing exposure condition and introducing active phase control technique, we had successfully developed VPH
grating for optical communication wavelength (1550 nm) with diffraction efficiency over 90% (TE mode) and a high
refractive index modulation of 0.047. We extend these techniques to the device for astronomical observation, aiming at
the application of K band VPH gratings for MOIRCS of the Subaru Telescope. The resultant grating has attained high
diffraction efficiency of 91.5%, spectral bandwidth (FWHM) 320 nm, and small wavefront error 0.03 waves in r.m.s. at
2200 nm. This VPH grism is a promising dispersion device for astronomical observation in near-infrared region.
Slanted fringe volume phase holographic gratings in astronomical instrumentation
Show abstract
Many existing astronomical spectrographs have been retrofitted with volume phase holographic gratings (VPHGs), since
at higher line density they are significantly more efficient than surface relief transmission gratings. Designing the
spectrograph around the VPHG offers additional advantages. In this paper we describe slanted fringe VPHG that are
considered as cross-disperser / beam expander in high-resolution echelle spectrographs for the Combined Incoherent
Focus of the VLT and the E-ELT. We will present simulations of diffraction efficiency of slanted fringe VPHGs that
explore the useful parameter space of these devices in terms of efficiency, line density and anamorphic beam expansion.
Cryogenic VPH grisms for MOIRCS
Show abstract
We present the development and first astronomical applications of VPH grisms which are now operated at
cryogenic temperature in MOIRCS, a Cassegrain near-infrared instrument of the Subaru Telescope. We designed
and fabricated the VPH grisms with a resolving power ~3000 for the use in near-infrared bands. The VPH
grating, encapsulated in BK7 glass, is glued between two ZnSe prisms with vertex angle of 20 deg. After
repeating several thermal cycles down to ~100 K carefully enough not to cause irreparable damage on the
grism during cooling, we evaluated the performance at cryogenic temperature in the laboratory and found no
deterioration and no large difference in the performance from that measured in room temperature. Based on
commissioning observations with MOIRCS, we have confirmed the high efficiency (~0.8) and the resolving power
of the original design. Common use of the grisms is due to start in the second semester of 2008.
Instrumentation Techniques and Technologies II
The FIREBall fiber-fed UV spectrograph
Show abstract
FIREBall (Faint Intergalactic Redshifted Emission Balloon) had a successful first engineering flight in July of 2007 from
Palestine, Texas. Here we detail the design and construction of the spectrograph. FIREBall consists of a 1m telescope
coupled to a fiber-fed ultraviolet spectrograph flown on a short duration balloon. The spectrograph is designed to map
hydrogen and metal line emission from the intergalactic medium at several redshifts below z=1, exploiting a small
window in atmospheric oxygen absorption at balloon altitudes. The instrument is a wide-field IFU fed by almost 400
fibers. The Offner mount spectrograph is designed to be sensitive in the 195-215nm window accessible at our altitudes
of 35-40km. We are able to observe Lyα, as well as OVI and CIV doublets, from 0.3 < z < 0.9. Observations of UV
bright B stars and background measurements allow characterization of throughput for the entire system and will inform
future flights.
MAGIQ at the W. M. Keck Observatory: initial deployment of a new acquisition, guiding, and image quality monitoring system
Show abstract
The W. M. Keck Observatory has completed the development and initial deployment of MAGIQ, the Multi-function
Acquisition, Guiding and Image Quality monitoring system. MAGIQ is an integrated system for acquisition, guiding and
image quality measurement for the Keck telescopes. This system replaces the acquisition and guiding hardware and
software for existing instruments at the Observatory and is now the standard for visible wavelength band acquisition
cameras for future instrumentation. In this paper we report on the final design and implementation of this new system,
which includes three major components: a visible wavelength band acquisition camera, image quality measurement
capability, and software for acquisition, guiding and image quality monitoring. The overall performance is described, as
well as the details of our approach to integrating low order wavefront sensing capability in order to provide closed loop
control of telescope focus.
Design and status of the optical corrector for the DES survey instrument
Show abstract
The DECam instrument, for the 4m Blanco telescope at CTIO, is a 5 lens element wide field camera giving a 2.2 degree
diameter field of view. The lenses are large, with the biggest being 980mm in diameter, and this poses challenges in
mounting and alignment. This paper reports the status of the production of the optics for the DECam wide field imager
Also presented are the design and finite element modelling of the cell design for the 5 lenses of the imager along with the
proposed alignment process.
Deploying comb and tunable lasers to enable precision radial velocity surveys
Show abstract
We describe recent progress toward developing optical frequency laser combs and tunable laser to the problem of more
precise calibration of high dispersion astronomical spectra, thus permitting radial velocity determinations in the few
cm/sec regime. We describe two programs in progress to calibrate both a cross dispersed echelle spectrograph with a
laser comb and to calibrate a multiobject echelle spectrograph with a tunable laser.
Instrumentation Techniques and Technologies III
X-shooter near-IR spectrograph arm realisation
Show abstract
X-shooter is a new high-efficiency spectrograph observing the complete spectral range of 300-2500 nm in a single
exposure, with a spectral resolving power R>5000. The instrument will be located at the Cassegrain focus of one of the
VLT UTs and consists of three spectrographs: UV, VIS and Near-IR. This paper addresses the design, hardware
realization and performance of the Near-IR spectrograph of the X-Shooter instrument and its components.
Various optical, mechanical and cryogenic manufacturing and verification techniques are discussed. The cryogenic
performance of replicated light weight gratings is presented. Bare aluminium mirrors are produced and polished to
optical quality to preserve high shape accuracy at cryogenic conditions. Their manufacturing techniques and
performance are both discussed. The cryogenic collimator and dispersion boxes, on which the optical components are
mounted, feature integrated baffles for improved stiffness and integrated leaf springs to reduce tension on optical
components, thereby challenging 5 axis simultaneous CNC milling capabilities. ASTRON Extreme Light Weighting is
used for a key component to reduce the flexure of the cryogenic system; some key numbers and unique manufacturing
experience for this component are presented. The method of integrated system design at cryogenic working temperatures
and the resulting alignment-free integration are evaluated. Finally some key lab test results for the complete NIR
spectrograph are presented.
NICI: combining coronagraphy, ADI, and SDI
Show abstract
The Near-Infrared Coronagraphic Imager (NICI) is a high-contrast AO imager at the
Gemini South telescope. The camera includes a coronagraphic mask and dual channel imaging
for Spectral Differential Imaging (SDI). The instrument can also be used in a fixed Cassegrain
Rotator mode for Angular Differential Imaging (ADI). While coronagraphy, SDI, and ADI have
been applied before in direct imaging searches for exoplanets. NICI represents the first time that
these 3 techniques can be combined. We present preliminary NICI commissioning data using
these techniques and show that combining SDI and ADI results in significant gains.
Lambert: a novel compact calibration solution for superior telescope flat fielding
Show abstract
Traditional dome flat fielding methods typically have difficulties providing spatially uniform illumination and adequate
flux over a telescopic instrument's entire spectral range. Traditional flat fielding screens, with an illumination source at
least the size of the primary, can be difficult or impractical to mount and uniformly illuminate. The Las Cumbres
Observatory Global Telescope Network (LCOGTN) will consist of approximately 50 robotic telescopes of 0.4 m, 1.0 m,
and 2.0 m apertures with instrument bandwidth ranging from 350 - 1800 nm. The network requires a robust flat-field
solution to fit in compact enclosures.
A scanning illuminated flat fielding bar, Lambert, was developed to meet these requirements. Illumination is from a
linear arrangement of sources that are spatially dispersed by a narrow holographic or glass diffuser equal in length to the
primary's diameter. We have investigated a linearly scanning, enclosure mounted, deployable unit, and a rotary scanning,
telescope mounted unit. For complete visible-light bandwidth, a set of different color LEDs is used. The source density,
scan speed, and variable intensity tunes the flux to the instrument wavelength and bandwidth. The Lambert flat fields in
comparison to sky flats match pixel to pixel variations better than 0.5%; large scale illumination differences, which are
stable and repeatable, are ~1%.
FLEX - the first light explorer: a fully OH-suppressed near-infrared integral field spectrograph
Show abstract
FLEX is a concept for a fully OH suppressed near infrared integral field spectrograph, being developed at the AAO.
FLEX will be the first instrument to employ fibre Bragg gratings for OH suppression, a radical new technology which
cleanly suppresses the atmospheric OH emission lines at 30dB whilst maintaining a high overall throughout of ~90%. In
this paper we simulate the expected performance of FLEX, and discuss its impact on the science case. FLEX will
effectively make the near-infrared sky 4 mags fainter in the H band and 3 mags fainter in the J band, offering
unprecedentedly deep views of the near-infrared Universe. The FLEX concept is optimised for the identification of the
sources of first light in the Universe - high redshift galaxies or quasars identified through Lyman-alpha emission or a
Lyman break in the continuum spectrum. As such it will consist of a 2x2" integral field unit, composed of a 61 lenslet
hexagonal array, feeding an existing moderate spectral resolution spectrograph, via an OH-suppression unit. We have
simulated the performance of FLEX and show that it can provide robust identification of galaxies at the epoch of
reionisation. A FLEX-like instrument on an ELT could measure the ionisation and enrichment of the inter-galactic
medium beyond a redshift of 7 via metal absorption lines.
Design of compact integral field spectrometers for mid- to high-resolving powers using immersed gratings
Show abstract
We present designs for compact near-IR spectrometers with mid to high resolving powers. They use an innovative
combination of integral-field units and immersed gratings, both with and without cross-dispersion. The advent of ELTs
with scientific requirements for multi-channel instruments (e.g. EAGLE) with high resolving powers has led to designs
for spectrometers which are made more compact by using immersed gratings and are capable of high spectral resolving
power by including cross dispersion and an arrangement of the IFU output that provides the requisite short slit.
Posters: UV/VIS/IR Instrumentation
Lessons learned from VISIR
Show abstract
VISIR is the VLT mid-infrared (mid-IR) Imager and Spectrometer. Since 2004, it provides data at high spatial
and spectral resolutions in the N (8-13 μm) and Q (16-24 μm) atmospheric windows. VISIR observations have
provided unique constraints on targets such as central regions of nearby galaxies, or protoplanetary disks. We
review here VISIR Imager and Spectrometer characteristics, emphasizing on some current limitations because
of various undesirable effects. Its successor on an ELT will provide data with a unique sharpness (0.05") and
sensitivity (35 μJy source detectable in 1 hour at 10 σ level), thus allowing a characterization of exoplanetary
disks and inner exoplanets with an unprecedent precision. At the light of VISIR experience, we discuss how
the lessons learned from VISIR can be turned to good account for designing and operating the future mid-IR
instrument on the European ELT.
LIINUS/SERPIL: a design study for interferometric imaging spectroscopy at the LBT
Show abstract
We present two design concepts and the science drivers of a proposed near-infrared interferometric integral field
spectrograph for the LBT. This instrument will expand the capabilities of the currently-under-construction
interferometric camera LINC-NIRVANA with spectroscopy by means of an integral field unit (IFU) located inside the
LINC cryostat. Two instrument concepts have been studied in detail: a microlens array IFU with a spectrograph built
entirely inside LINC (the LIINUS approach), and a lenslet+fibers IFU feeding an external spectrograph (the SERPIL
approach). In both cases, the instrument incorporates imaging interferometry with integral field spectroscopy, an ideal
combination for detailed studies of astronomical objects down to below 10mas angular resolution in the near-infrared.
The scientific applications range from solar system studies and spectroscopy of exoplanets to the dynamics of stars and
gas in the central regions of the Milky Way and other nearby galaxies.
Fabrication of slicer optics of mid-infrared spectrometer with an image slicer (MIRSIS) for ground-based astronomy
Show abstract
Mid Infrared Spectrometer with an Image Slicer (MIRSIS) is a compact mid-infrared spectrometer with an image slicer
as a testbed of techniques for efficient observations with next generation telescopes. MIRSIS is a 10-micron band
spectrometer for ground-based observations. Optics of MIRSIS is mostly composed of reflective ones. A key point of the
development of MIRSIS is a fabrication of slicer optics, which consists of slice mirrors, pupil mirrors and pseudo slit
mirrors. It is necessary to develop fabrication technique of slicer optics, because shapes and alignment of these mirrors
are special. Here it is also important to choose the design matched to the processing method. In this paper, we report our
fabrication of the slicer optics elements in detail. As a result, we achieved the slice mirror with the micro-roughness of
RMS 12nm and the angle accuracy of under 0.0041deg, the pupil mirror with the micro-roughness of RMS 20nm and
the shape accuracy of PV 3micron, and the pseudo slit mirror with the angle accuracy of 0.02deg. All of the parts
fabricated satisfy the required specification.
A new mid-infrared camera for ground-based 30 micron observations: MAX38
Show abstract
We are developing a new infrared camera MAX38 (Mid-infrared Astronomical eXplorer) for long mid-infrared (25-40
micron) astronomy for the Univ. of Tokyo Atacama 1.0-meter telescope which is the world highest infrared telescope at
5,640m altitude. Thanks to the high altitude and dry weather condition of the Atacama site we can access the 30-micron
wavelength region from ground-based telescopes for the first time in the world. We employ a Si:Sb 128×128 array
detector to cover the wide mid-infrared wavelength range from 8 to 38 micron.
The development of the MAX38 has been almost completed. Test observations in N-band wavelength at Hiroshima
Kanata telescope (Hiroshima, Japan) was successfully carried out on June 2007 and March 2008. The first 30-micron
observation at Atacama is scheduled in the spring of 2009.
A mid-infrared polarization capability for the ELT
Show abstract
Imaging- and spectropolarimetry in the thermal infrared (~ 5-30 μm) can inform us about two important open
questions in modern astrophysics - namely the role of magnetism in the formation of stars, and the life-cycle
of cosmic dust. These are key questions outlined in the document "A Science Vision for European Astronomy"
by de Zeeuw & Molster (2007). Thermal IR polarimetry is the only technique that can peer into the heart of
star forming cores, where an infant star heats its immediate surroundings to temperatures of several hundred
Kelvin. The polarization itself is induced by a preferential alignment of the spin axis of cosmic dust grains, a
process ultimately controlled by the ambient magnetic field. The spectrum is sensitively dependent on the grain
optical properties, structure and shape, thus providing information not otherwise obtainable by conventional
spectroscopy. The MIRI instrument on the JWST will not have a polarimetry mode, thus leaving open the
possibility of an ELT mid-IR instrument being able to make substantial progress on these fundamental issues.
Before describing the advantages of a mid-IR spectropolarimeter on an ELT, we first present some preliminary
results from our polarization observations with the TIMMI2 mid-IR instrument between 2004 and 2006. The
experience gained with TIMMI2 - in terms of technical issues and observing strategy - will inform the design of
any future instrument. Following this we will describe the science that could be done with an ELT instrument,
and some of the basic design parameters. For instance, with a resolution of ~ 70 milli-arcseconds (FWHM at
10 μm) it will become possible to resolve the magnetic field configuration in the circumstellar disks and bipolar
outflows of young stars at a spatial scale of less than 10 AU in the nearest star formation regions. This will
strongly constrain hydromagnetic models - the favoured means of extracting angular momentum and allowing
accretion to proceed - for bipolar jets emanating from a range of compact astrophysical objects. Further, with
a resolving power of order 200, and sensitivity of 100σ in 1 hour integration on a 0.5 mJy point source, the
evolution of cosmic dust - and the governing physical and chemical processes - from its formation in old stellar
outflows to its deposition in planet-forming disks, will become amenable to detailed polarization studies.
A large free-standing wire grid for microwave variable-delay polarization modulation
Show abstract
One technique for mapping the polarization signature of the cosmic microwave background uses large, polarizing grids
in reflection. We present the system requirements, the fabrication, assembly, and alignment procedures, and the test
results for the polarizing grid component of a 50 cm clear aperture, Variable-delay Polarization Modulator (VPM). This
grid is being built and tested at the Goddard Space Flight Center as part of the Polarimeter for Observing Inflationary
Cosmology at the Reionization Epoch (POINCARE).
For the demonstration instrument, 64 μm diameter tungsten wires are being assembled into a 200 μm pitch, free-standing
wire grid with a 50 cm clear aperture, and an expected overall flatness better than 30 μm. A rectangular,
aluminum stretching frame holds the wires with sufficient tension to achieve a minimum resonant frequency of 185 Hz,
allowing VPM mirror translation frequencies of several Hz. A lightly loaded, flattening ring with a 50 cm inside
diameter rests against the wires and brings them into accurate planarity.
Development of mid-infrared spectrometer with an image slicer (MIRSIS) for ground-based astronomy: developing optical and mechanical mounts
Show abstract
Mid-Infrared Spectrometer with an Image Slicer (MIRSIS) is a 10micron band spectrometer for ground-based
observations. Based on the optical design reported in Okamoto et al. (2006), we recently developed most of
optical elements and their mounts. There, we adopted designs based on an ultra-precision cut for the slice mirrors
and the pupil mirrors. We also designed and partly manufactured the optical parts with switching/adjusting
mechanism with cryogenic step motors. Since MIRSIS has a very complicated stereoscopic configuration of
optical elements, we developed a method to adjust the optical alignment where relative positional markers and
a three-dimensional measuring system are combined. We confirmed that we can achieve position and angular
adjustment with error down to 0.1mm and 0.05degree through alignment test with a pair of mirrors.
A silicon and KRS-5 grism suite for FORCAST on SOFIA
Show abstract
We have designed and fabricated a suite of grisms for use in FORCAST, a mid-infrared camera scheduled as a
first-light instrument on SOFIA. The grism suite gives SOFIA a new capability: low and moderate resolution
spectroscopy from 5μm to 37μm, without the addition of a new instrument. One feature of the optical design
is that it includes a mode using pairs of cross-dispersed grisms, providing continuous wavelength coverage over
a broad range at higher resolving power. We fabricated four silicon (n = 3.44) grisms using photolithographic
techniques and purchased two additional mechanically ruled KRS-5 (n = 2.3) grisms. One pair of silicon grisms
permits observations of the 5 - 8μm band with a long slit at R~ 200 or, in a cross-dispersed mode, at resolving
powers up to 1500. In the 8 - 14μm region, where silicon absorbs heavily, the KRS-5 grisms produce resolving
powers of 300 and 800 in long-slit and cross-dispersed mode, respectively. The remaining two silicon grisms cover
17 - 37μm at resolving powers of 140 and 250. We have thoroughly tested the silicon grisms in the laboratory,
measuring efficiencies in transmission at 1.4 - 1.8μm. We report on these measurements as well as on cryogenic
performance tests of the silicon and KRS-5 devices after installation in FORCAST.
Direct thermal imaging of circumstellar discs and exo-planets
Show abstract
The phase A study of a mid infrared imager and spectrograph for the European Extremely Large Telescope (E-ELT), called METIS, was endorsed in May 2008. Two key science drivers of METIS are: a) direct thermal imaging of exo-planets and b) characterization of circumstellar discs from the early proto-planetary to the late
debris phase. Observations in the 10μm atmospheric window (N band) require a contrast ratio between stellar light and emitted photons from the exo-planet or the disc of ~ 105. At shorter wavelengths the contrast between star and reflected light from the planet-disc system exceeds ≳ 107 posing technical challenges. By means of end-to-end detailed simulations we demonstrate that the superb spatial resolution of a 42m telescope in combination with stellar light rejection methods such as coronagraphic or differential imaging will allow detections at 10μm for a solar type system down to a star-planet separation of 0.1" and a mass limit for irradiated planets of 1 Jupiter (MJ) mass. In case of self-luminous planets observations are possible further out e.g. at the separation limit of JWST of ~ 0.7", METIS will detect planets ≳5MJ. This allows to derive a census of all such exo-planets by means of thermal imaging in a volume limited sample of up to 6pc. In addition, METIS will provide the possibility to study the chemical composition of atmospheres of exo-planets using spectroscopy at moderate spectral resolution (λ/Δλ ~ 100) for the brightest targets. Based on detailed performance and sensitivity estimates, we demonstrate that a mid-infrared instrument on an ELT is perfectly suited to observe gravitationally created structures such
as gaps in proto- and post- planetary discs, in a complementary way to space missions (e.g. JWST, SOFIA) and ALMA which can only probe the cold dust emission further out.
Laboratory performance characteristics of CanariCam, the GTC facility multi-mode mid-IR camera
Show abstract
CanariCam is the facility multi-mode mid-IR camera developed by the University of Florida (UF) for the 10.4-
meter Gran Telescopio Canarias (GTC). CanariCam contains a 320 × 240-pixel Raytheon array, which will
Nyquist-sample the diffraction-limited point-spread-function at wavelengths longer than 8 microns, yielding a
field of view of 26"×19". In Aug. 2007, the University of Florida instrument team held a successful Acceptance
Testing (AT) of CanariCam. We describe key performance requirements, and compare these to the actual performance
during formal AT. Among the results considered are detector noise characteristics, image quality, and
throughput. We focus particularly on the unique dual-beam polarimetric modes. We have demonstrated that
with a half-wave plate, it achieves or exceeds the design goals for imaging both polarization planes simultaneously.
FORCAST: the first light instrument for SOFIA
Show abstract
FORCAST has been selected to be the "first light" U.S. science instrument aboard SOFIA. FORCAST will offer dual
channel imaging in discrete filters at 5 - 25 microns and 30 - 40 microns, with diffraction-limited imaging at wavelengths
> 15 microns. FORCAST will have a plate scale of 0.75 arcsec per pixel, giving it a 3.2 arcmin x 3.2 arcmin FOV on
SOFIA. We give a status update on FORCAST, including filter configuration for SOFIA's early science phase;
anticipated in-flight performance; SOFIA facility testing with FORCAST; ground-based testing performance at Palomar
Observatory; performance of its new dichroic beamsplitter; and a preliminary design of the in-flight calibration box.
Optical properties of astronomical silicates
Show abstract
Correct interpretation of a vast array of astronomical data relies heavily on understanding the properties of silicate dust
as a function of wavelength, temperature, and crystallinity. We introduce the OPASI-T (Optical Properties of
Astronomical Silicates with Infrared Techniques) project to address the need for high fidelity optical characterization
data on the various forms of astronomical dust. We use two spectrometers to provide extinction data for silicate samples
across a wide wavelength range (from the near infrared to the millimeter). New experiments are in development that will
provide complementary information on the emissivity of our samples, allowing us to complete the optical
characterization of these dust materials. In this paper, we present initial results from several materials including
amorphous iron silicate, magnesium silicate and silica smokes, over a wide range of temperatures, and discuss the design
and operation of our new experiments.
Design of a mid-IR polarimeter for SOFIA
Show abstract
Mid-infrared polarimetry remains an underexploited technique; where available it is limited in spectral coverage from
the ground, and conspicuously absent from the Spitzer, JWST and Herschel instrument suites. The unique characteristics
of SOFIA afford unprecedented spectral coverage and sensitivity in the mid-infrared waveband. We discuss the
preliminary optical design for a 5-40μm spectro-polarimeter for use on SOFIA, the SOFIA Mid-InfraRed Polarimeter
(SMIRPh). The design furthers the existing 5-40μm imaging and spectroscopic capabilities of SOFIA, and draws on
experience gained through the University of Florida's mid-IR imagers, spectrometer and polarimeter designs of T-ReCS
and CanariCam. We pay special attention to the challenges of obtaining polarimetric materials suitable at both these
wavelengths and cryogenic temperatures. Finally, we (briefly) present an overview of science highlights that could be
performed from a 5-40μm imaging- and spectro-polarimeter on SOFIA. Combined with the synergy between the
possible future far-IR polarimeter, Hale, this instrument would provide the SOFIA community with unique and exciting
science capabilities, leaving a unique scientific legacy.
Science of active galactic nuclei with the GTC and CanariCam
Show abstract
CanariCam is the facility mid-infrared (MIR) instrument for the Gran Telescopio Canarias (GTC), a 10.4m
telescope at the Observatorio del Roque de los Muchachos on La Palma. One of the science drivers for CanariCam is the study of active galactic nuclei (AGN). We will exploit the instrument's high sensitivity in imaging,
spectroscopy, and polarimetry modes to answer fundamental questions of AGN and their host galaxies. Dust in
the nucleus of an active galaxy reprocesses the intrinsic radiation of the central engine to emerge in the MIR.
Current work demonstrates that the hot dust immediately associated with the AGN, which blocks direct views of
the AGN from some lines of sight, is confined to small (parsec) scales. Thus, high spatial resolution is essential to
probe the "torus" of unified AGN models separate from the host galaxy. CanariCam provides a 0.08" pixel scale
for Nyquist sampling the diffraction-limited point spread function at 8μm, and narrow (0.2") spectroscopy slits
(with R=120-1300). New observations with the GTC/CanariCam will provide key constraints on the physical
conditions in the clumpy torus, and we will sensitively determine AGN obscuration as a function of nuclear
activity. We will therefore address the fueling process and its relationship to the torus, the interaction with the
host galaxy, and dust chemistry. These data will be essential preparation for the next generation of telescopes
that will observe the distant universe directly to explore galaxy and black hole formation and evolution, and the
GTC/CanariCam system uniquely provides multiple modes to probe AGN.
10 meter airborne observatory
Show abstract
Inside an aircraft fuselage there is little room for the mass of all the instrumentation of a ground-based observatory much
less a primary objective aperture at the scale of 10 meters. We have proposed a solution that uses a primary objective
grating (POG) which matches the considerable length of the aircraft, approximately 10 meters, and conforms to aircraft
aerodynamics. Light collected by the POG is diffracted at an angle of grazing exodus inside the aircraft where it is
disambiguated by an optical train that fits within to the interior tunnel. Inside the aircraft, light is focused by a parabolic
mirror onto a spectrograph slit. The design has a special benefit in that all objects in the field-of-view of the free spectral
range of the POG can have their spectra taken as the aircraft changes orientation. We suggest flight planes that will
improve integration times, angular resolution and spectral resolution to acquire targets of high stellar magnitudes or
alternatively increase the number of sources acquired per flight at the cost of sensitivity.
Solving the three cross-talk flavors on WIRCam and its HAWAII-2RG detectors
Show abstract
The Wide field Infrared Camera (WIRCam) is one of the 3 workhorse instruments in operation at CFHT. It's
mosaic of four HAWAII-2RG is read using two SDSU-III controllers with 32-amplifiers in parallel per detector.
First-light images showed that WIRCam suffered from three flavors of cross-talk: the "positive", "negative" and
"edge" cross-talks. All have now been eliminated at the source and WIRCam is now cross-talk free. Two of
these cross-talks originated from the controller electronic and one, the "edge" cross-talk, is intimately linked
to the HAWAII-2RG detector and its description may be of a broader interest for other instruments using
these detectors. We present the three cross-talk flavors and the hardware or software solutions implemented to
eliminate them.
The Canarias InfraRed Camera Experiment (CIRCE): progress of the opto- and cryo- mechanical design and manufacture
Show abstract
We present the current status of the Canarias InfraRed Camera Experiment (CIRCE) an all-reflective near-IR,
imager, spectrograph, and polarimeter for the 10.4-meter Gran Telescopio Canarias (GTC). In particular, we
review the progress of the opto- and cryo- mechanical design and manufacture, focusing on the custom filter,
lyot, and grism wheels, lightweight optics, and mirror brackets. We also outline our progress with the optical
bench. Finally, we discuss a number of CIRCE's features that both complement and augment the planned suite
of GTC facility instruments.
Polarimetric capabilities with the Canarias InfraRed Camera Experiment (CIRCE)
Show abstract
The Canarias InfraRed Camera Experiment (CIRCE) for the Gran Telescopio Canarias (GTC) is one of the few infrared
instruments in the world using a four-beam polarimeter. The classical double-beam configuration consists of a half-wave
plate (HWP) and a Wollaston Prism (WP) that allow measurement of two linear polarization components of the
light in a single exposure. Instead, our instrument includes a WeDoWo - a dual-WP system with principal axis at 45
degrees that is inserted near the pupil plane. Thus, all linear Stokes parameters can be obtained in a single observation.
We can also perform medium-resolution (R=400-1500) spectro-polarimetry by inserting a grism in the beam. The
CIRCE focal plane mask includes three field stops for imaging polarimetry, three slits for spectropolarimetry and three
slits for regular spectroscopy of nearby sources. CIRCE also has a high-speed photometry mode that, combined with
polarimetry on a large telescope such as the GTC, will provide important insights into highly-variable sources such as
microquasars.
Readout electronics and fast photometry with the Canarias InfraRed Camera Experiment (CIRCE)
Show abstract
We present the design for a high-speed readout imaging mode for the Canarias InfraRed Camera Experiment (CIRCE), a
visitor-class near-IR imager, spectrograph, and polarimeter for the 10.4 meter Gran Telescopio Canarias (GTC). This
mode, along with the polarimetric and spectroscopic capabilities of the instrument will provide a powerful and unique
instrument for the study of fast variability objects. Modification in the firmware of the readout control electronics of the
HAWAII-2 2048×2048 detector will allow us to select the effective detector size and hence reduce the readout time. We
present a description of the final design along with a discussion of potential future improvements.
AIR-C: Antarctic infra-red camera
Show abstract
This paper details the design process for AIR-C, the Antarctic Infra-Red Camera, for use with Tohoku University's 40
cm Antarctic telescope. The camera will also be compatible with the planned 2 meter class Japanese telescope at Dome
F. First, we review of the design requirements which shaped the development process. The optical chain receives the
most detailed discussion. The other components will be discussed briefly. The effect of cryogenic temperatures on the
lenses was taken into account during the design process. AIR-C's performance is predicted. Finally, we discuss the
scientific potential for a small Antarctic telescope.
Smithsonian Widefield Infrared Camera
Show abstract
The Smithsonian Widefield Infrared Camera (SWIRC) is a Y -, J-, and H-band imager for the f/5 MMT.
Proposed in May 2003 and commissioned in June 2004, the goal of the instrument was to deliver quickly a wide
field-of-view instrument with minimal optical elements and hence high throughput. The trade-off; was to sacrifice
K-band capability by not having an internal, cold Lyot stop. We describe SWIRC's design and capabilities, and
discuss lessons learned from the thermal design and the detector mount, all of which have been incorporated into
the upcoming MMT & Magellan Infrared Spectrograph.
Preliminary optical design of PANIC, a wide-field infrared camera for CAHA
Show abstract
In this paper, we present the preliminary optical design of PANIC (PAnoramic Near Infrared camera for Calar Alto), a
wide-field infrared imager for the Calar Alto 2.2 m telescope. The camera optical design is a folded single optical train
that images the sky onto the focal plane with a plate scale of 0.45 arcsec per 18 μm pixel. A mosaic of four Hawaii 2RG
of 2k x 2k made by Teledyne is used as detector and will give a field of view of 31.9 arcmin x 31.9 arcmin. This
cryogenic instrument has been optimized for the Y, J, H and K bands. Special care has been taken in the selection of the
standard IR materials used for the optics in order to maximize the instrument throughput and to include the z band. The
main challenges of this design are: to produce a well defined internal pupil which allows reducing the thermal
background by a cryogenic pupil stop; the correction of off-axis aberrations due to the large field available; the
correction of chromatic aberration because of the wide spectral coverage; and the capability of introduction of narrow
band filters (~1%) in the system minimizing the degradation in the filter passband without a collimated stage in the
camera. We show the optomechanical error budget and compensation strategy that allows our as built design to met the
performances from an optical point of view. Finally, we demonstrate the flexibility of the design showing the
performances of PANIC at the CAHA 3.5m telescope.
PANIC: the new panoramic NIR camera for Calar Alto
Show abstract
PANIC is a wide-field NIR camera, which is currently under development for the Calar Alto observatory (CAHA) in
Spain. It uses a mosaic of four Hawaii-2RG detectors and covers the spectral range from 0.8-2.5 μm (z to K-band). The
field-of-view is 30×30 arcmin. This instrument can be used at the 2.2m telescope (0.45arcsec/pixel, 0.5×0.5 degree
FOV) and at the 3.5m telescope (0.23arcsec/pixel, 0.25×0.25 degree FOV).
The operating temperature is about 77K, achieved by liquid Nitrogen cooling. The cryogenic optics has three flat folding
mirrors with diameters up to 282 mm and nine lenses with diameters between 130 mm and 255 mm. A compact filter
unit can carry up to 19 filters distributed over four filter wheels. Narrow band (1%) filters can be used.
The instrument has a diameter of 1.1 m and it is about 1 m long. The weight limit of 400 kg at the 2.2m telescope
requires a light-weight cryostat design. The aluminium vacuum vessel and radiation shield have wall thicknesses of only
6 mm and 3 mm respectively.
First light with NEWFIRM
Show abstract
NEWFIRM, the widefield infrared camera for the NOAO 4-m telescopes, saw first light in February 2007 and is now in
service as a general user instrument. Previous papers have described it conceptually and presented design details. We
discuss experience gained from assembly, laboratory testing, and on-sky commissioning. We present final system
performance characteristics and summarize science use in its the first semester of general availability. NEWFIRM has
met its requirement to provide a high efficiency observing system, optimized end-to-end for survey science.
ANIR: Atacama near infrared camera for Paschen alpha imaging
Show abstract
We have been developing a near infrared camera called ANIR (Atacama Near InfraRed camera), for the University
of Tokyo Atacama 1.0m telescope installed at the summit of Co. Chajnantor (5640m altitude) in Northern Chile.
The major aim of this camera is to carry out an imaging survey in Paschen α emission line (1.8751μm) from
the ground for the first time. The camera is based on a PACE-HAWAII2 array with an Offner relay optics for
re-imaging, and field of view is 5.'3 × 5.'3 with pixel scale of 0."308/pix. It is scheduled to see first light in the
end of 2008, and start the Paschen α/β survey of the Galactic plane in 2009.
The FourStar infrared camera
Show abstract
The FourStar infrared camera is a 1.0-2.5 μm (JHKs) near infrared camera for the Magellan Baade
6.5m telescope at Las Campanas Observatory (Chile). It is being built by Carnegie Observatories and
the Instrument Development Group and is scheduled for completion in 2009. The instrument uses four
Teledyne HAWAII-2RG arrays that produce a 10.9' × 10.9' field of view. The outstanding seeing at the
Las Campanas site coupled with FourStar's high sensitivity and large field of view will enable many
new survey and targeted science programs.
Performance of the WIYN high-resolution infrared camera
Show abstract
We present the design overview and on-telescope performance of the WIYN High Resolution Infrared Camera
(WHIRC). As a dedicated near-infrared (0.8-2.5 μm) camera on the WIYN Tip-Tilt Module (WTTM), WHIRC will
provide near diffraction-limited imaging with a typical FWHM of ~0.25". WHIRC uses a 2048 x 2048 HgCdTe array
from Raytheon's VIRGO line, which is a spinoff from the VISTA project. The WHIRC filter complement includes J, H
KS, and 10 narrowband filters. WHIRC's compact design makes it the smallest near-IR camera with this capability. We
determine a gain of 3.8 electrons ADU-1 via a photon transfer analysis and a readout noise of ~27 electrons. A measured
dark current of 0.23 electrons s-1 indicates that the cryostat is extremely light tight. A plate scale of 0.098" pixel-1 results
in a field of view (FOV) of ~3' x 3', which is a compromise between the highest angular resolution achievable and the
largest FOV correctable by WTTM. Measured throughput values (~0.33 in H-band) are consistent with those predicted
for WHIRC based on an elemental analysis. WHIRC was delivered to WIYN in July 2007 and was opened for shared
risk use in Spring 2008. WHIRC will be a facility instrument at the WIYN telescope enabling high definition near-infrared
imaging studies of a wide range of astronomical phenomena including star formation regions, proto-planetary
disks, stellar populations and interstellar medium in nearby galaxies, and supernova and gamma-ray burst searches.
Cryogenic tests of bimetallic diamond-turned mirrors for the FRIDA integral field unit
Show abstract
We describe diamond-turned material tests for the integral field unit (IFU) for the FRIDA instrument (inFRared Imager
and Dissector for the Adaptive optics system of the Gran Telescopio Canarias). FRIDA is closely based on the design of
the successful FISICA cryogenic infrared image slicing device, which used "monolithic" mirror arrays, diamond turned
into single pieces of metal. FRIDA, however, will require better roughness characteristics than the 15nm RMS of
FISICA to avoid light scatter in FRIDA's shorter wavelength limit (900nm). Al 6061 seems to be limited to this
roughness level by its silicate inclusions so some new combination of materials that are compatible with FRIDA's Al
6061 structure must be found. To this end, we have tested six diamond-turned mirrors with different materials and
different platings. We used the Zygo interferometer facility at IA-UNAM to do warm and cold profile measurements of
the mirrors to investigate possible bimetallic deformation effects. We present a detailed comparison of the various
performance characteristics of the test mirrors.
A wide-field near-infrared camera and spectrograph for the Mt. Abu 1.2 m telescope
Show abstract
We describe the design and optimization of a wide-field near-infrared camera and spectrograph (NICAS) for Mt Abu 1.2
m, f/13 Cassegrain telescope of Physical Research Laboratory. The principal science goals include photometric mapping
of star forming regions and medium resolution spectroscopy of Young Stellar Objects, evolved stars and transient
sources. The design goals are to achieve seeing-limited angular resolution in an un-vignetted field of view of ~ 8'x8' with
0.5" per pixel (of 18.5 μm) on a HgCdTe 1024×1024 infrared array, requiring a two-fold Cassegrain focal reduction. In
addition to the imaging, the instrument is required to have spectroscopic capability with a resolving power of 103 in the
0.85 - 2.5 μm region, needing a dispersion of 1 nm per pixel. Finally, since our telescope has a moderate aperture, the
throughput losses need to be minimized. The specifications are achieved by an optical design using 9 singlet lenses.
Only those lens materials are chosen for which measured values are available for refractive indices at 77 K (detector
operating temperature), changes of indices with temperature, and thermal coefficients of expansion. The design is
optimized to give sharpest images at 77 K. The optical path is folded by 90° after collimation by a fold-mirror and re-imaged
on the detector. The fold-mirror is replaced by a diffraction grating for spectrograph mode. In order to minimize
the reflection losses, all the lenses will be anti-reflection coated for the full operating wavelength range. Details of the
design are presented.
MOSFIRE: a multi-object near-infrared spectrograph and imager for the Keck Observatory
Show abstract
MOSFIRE, the multi-object spectrometer for infra-red exploration, is a near-IR (0.97-2.45 micron) spectrograph and
imager for the Cassegrain focus of the Keck I telescope. The optical design provides imaging and multi-object
spectroscopy over a field of view (FOV) of 6.14' x 6.14' with a resolving power of R~3,270 for a slit width of 0.7 arc
seconds (2.9 pixels along dispersion). The detector is a 2.5 micron cut-off 2K x 2K H2-RG HgCdTe array with a
SIDECAR ASIC for detector control. A special feature of MOSFIRE is that its multiplex advantage of up to 46 slits is
achieved using a cryogenic Configurable Slit Unit (developed in collaboration with the Swiss Centre for Electronics and
Micro Technology) reconfigurable under remote control in <5 minutes without thermal cycling. Slits are formed by
moving opposable bars from both sides of the focal plane. An individual slit has a length of ~7.1 arc seconds but bar
positions can be aligned to make longer slits. A single diffraction grating in two positions along with order-sorting filters
gives essentially full coverage of the K, H, J and Y bands using 3rd, 4th, 5th or 6th order respectively. The grating and a
mirror are mounted back-to-back, and when the bars are retracted from the FOV MOSFIRE becomes a wide-field
imager. A piezo tip-tilt mirror following the field lens is used to provide flexure compensation at the 0.1 pixel level. Two
large CCR heads allow the instrument to reach operating temperature in ~7 days. MOSFIRE is currently in construction.
Design options for high-performance high-resolution near-infrared spectrographs
Show abstract
The combination of immersion grating and infrared array detector technologies now allows the construction
of high-resolution spectrographs in the near-infrared that have capabilities approaching those of optical
spectrographs. It is possible, for instance, to design multi-object spectrographs with very large wavelength
coverage and high throughput. However, infrared spectrographs must be cryogenic and the cost of
complexity can be large. We investigate lower cost design options for single-object high-resolution
spectrographs. The trade-off in these designs is between the size/number of infrared arrays and the
inclusion of moving parts. We present a design for a no moving parts spectrograph with either 1.1-2.5 or 3-
5 μm simultaneous wavelength coverage. The design was undertaken with attention to cost as well as
scientific merit. Here we review the science drivers and key functional requirements. We present a general
overview of the instrument and estimate the limiting performance. The performance is compared with that
of medium-resolution infrared spectrographs as well as other high-resolution infrared spectrographs.
Designing the optimal semi-warm NIR spectrograph for SALT via detailed thermal analysis
Show abstract
The near infrared (NIR) upgrade to the Robert Stobie Spectrograph (RSS) on the Southern African Large Telescope
(SALT), RSS/NIR, extends the spectral coverage of all modes of the optical spectrograph. The RSS/NIR is a low to
medium resolution spectrograph with broadband, spectropolarimetric, and Fabry-Perot imaging capabilities. The optical
and NIR arms can be used simultaneously to extend spectral coverage from 3200 Å to approximately 1.6 μm. Both arms
utilize high efficiency volume phase holographic gratings via articulating gratings and cameras. The NIR camera
incorporates a HAWAII-2RG detector with an Epps optical design consisting of 6 spherical elements and providing subpixel
rms image sizes of 7.5 ± 1.0 μm over all wavelengths and field angles. The NIR spectrograph is semi-warm,
sharing a common slit plane and partial collimator with the optical arm. A pre-dewar, cooled to below ambient
temperature, houses the final NIR collimator optic, the grating/Fabry-Perot etalon, the polarizing beam splitter, and the
first three camera optics. The last three camera elements, blocking filters, and detector are housed in a cryogenically
cooled dewar. The semi-warm design concept has long been proposed as an economical way to extend optical
instruments into the NIR, however, success has been very limited. A major portion of our design effort entails a detailed
thermal analysis using non-sequential ray tracing to interactively guide the mechanical design and determine a truly
realizable long wavelength cutoff over which astronomical observations will be sky-limited. In this paper we describe
our thermal analysis, design concepts for the staged cooling scheme, and results to be incorporated into the overall
mechanical design and baffling.
Warm infrared echelle spectrograph (WINERED): testing of optical components and performance evaluation of the optical system
Show abstract
We are developing a new NIR high-resolution (Rmax = 100, 000) and high-sensitive spectrograph WINERED,
specifically customized for short NIR bands at 0.9-1.35 μm. WINERED employs the following novel approaches
in the optical system: portable design with a ZnSe immersion grating and warm optics without any cold stops.
These concepts result in several essential advantages: easy to build, align, and maintain; these result in a short
development time and low cost. WINERED is also equipped with a "normal echelle mode", which can cover
the entire wavelength range simultaneously with R = 30, 000. In this poster paper, we will present the results
of the detailed testing of optical components and the laboratory first light for the normal echelle mode. See
Poster paper 7018-183 by Ikeda et al. in another session for the status of the development of the ZnSe immersion
grating for R = 100, 000. We plan to complete the normal mode first by the end of 2008 and will install the
immersion grating in 2010.
High resolution spectrograph unit (HRU) for the SUBARU/IRCS
Show abstract
We present an upgrade plan of the infrared camera and spectrograph for the Subaru Telescope (IRCS1-4) to introduce the high resolution spectroscopic mode (a resolving power; R=λ/Δλ > 70,000) in the infrared bands
(1.4-5.5 μm). To realize the compact and stable cooled instrument, we are developing the immersion grating5 with Si whose refractive index is ~ 3.4. The optics design is significantly compact (600mm × 250mm × 250mm) using the Si immersion grating, and it can be easily located beside or inside the IRCS main dewar. The IRCS
has been operating for 8 years with an extremely stable condition, and it is combined with the next generation adaptive optics system (AO1886) and the laser guide star system (LGS7) of the Subaru Telescope. The quick integration of the new high resolution spectrograph unit (HRU) can be expected by using the existing stable
instrument. The total performance with the designed optics is so good that the optical design could meet the required specifications. The image quality shows a strehl ratio of > 0.88 for the entire bands, and 24 scannings of the gratings can cover the 1.4-5.5 μm. We plan to fabricate the Si immersion grating for the actual astronomical
use in 2009, and the HRU will be built around 2011. It will be the first high sensitive infrared spectrograph with high spectral resolution capability in the northern hemisphere and with the laser guide star AO system.
FLEX-the first light explorer: a pathfinder instrument for fibre Bragg grating OH suppression
Show abstract
We present FLEX, an instrument to demonstrate the power of fibre Bragg grating OH suppression. This ground
breaking technology promises great gains in sensitivity for near infrared instrumentation and the time is now
right for a pioneer instrument to prove the effectiveness of the technique. Our proposal is for an adaptive optics
fed integral field unit for an 8 metre class telescope. We envisage a 61 element IFU with 0.22" sampling and a
2.2" field of view. J and H-band OH suppression units would cleanly suppress the atmospheric emission lines,
effectively lowering the sky background by 3 or 4 magnitudes respectively. The capabilities of FLEX will make
it ideal for deep Epoch of Reionisation studies, as well as studies of star formation at z~1-4. To enable rapid
and economical deployment FLEX would use an existing near infrared spectrograph with R ≈ 1000 and employ
facility adaptive optics.
Straylight considerations for NIR spectrographs
Show abstract
Modern NIR spectrographs aiming at the detection and spectral study of faint deep sky objects are potentially sensitive to
performances-degrading straylight effects. In particular, the following straylight mechanisms have been identified:
- ghost images, inherent to large aperture broadband camera in multi-band spectrographs, have often specific
distribution which can (and needs to) be simulated when baffling is not possible;
- scattered light generated at the surface of the component is also interesting in the NIR spectrum as it is often at
the cross-over between a micro-roughness dominated behaviour and a particulate contamination dominated one;
- the use of dispersing element such as diffraction grating brings its own straylight issues related to the control
of non-evanescent orders and under incidence different from the one given by the main sequential optical path from
telescope to detector;
- finally, thermal background from local spectrograph environment or more remote observatory-level sources
affects particularly the long wavelength end of the NIR spectrum (H and K bands typically) and in-band or out-of-band
rejection is desirable as complementary or even alternative to potentially complex and costly full cryogenic operation.
These different points are discussed and illustrated through case studies of several NIR multi-object spectrograph designs
like the fibre-fed reflective grating with OH lines suppression FMOS (designed and built), the broadband multi-IFU
slicer and slit grating KMOS (under development) and the fibre-fed grism-based SIDE (in conceptual design stage).
ISLE: near-infrared imager/spectrograph for the 1.88m Telescope at Okayama Astrophysical Observatory
Show abstract
ISLE is a near-infrared imager and spectrograph for the Cassegrain focus (f/18) of the 1.88 m telescope at
Okayama Astrophysical Observatory. It is upgraded instrument with a new detector, HAWAII-1 HgCdTe array
and new optics. ISLE provides imaging capabilities which covers 4.2 × 4.2 arcmin2 field-of-view at 0.25 arc-sec/
pixel and long-slit (4 arcmin) spectroscopic capabilities at λ/Δλ = 1000 - 4000 using reflection gratings.
The noise performance of the detector is excellent. The read noise of 2.5 electrons with 25 Fowler pairs has
been achieved, that is one of the world's lowest level among the instruments which use HAWAII-1 array as the
detector. We discuss the technical performance of ISLE and examine the upgrade effectiveness.
OSIRIS optical integration and tests
Show abstract
The Optical System for Imaging and low Resolution Integrated Spectroscopy (OSIRIS) is the first light instrument for
the 10.4 meters Gran Telescopio de Canarias (GTC). It's a 8.5 × 8.5 arc-min visible camera; a set of grisms provides low
resolution spectroscopic capability.
In this contribution the accessories and mountings for alignment are presented as well as the techniques used. Also, a
complete characterization of the system at laboratory for image quality, spectral and spatial resolution, and image
movement, etc. are shown.
Control system for the AMICA infrared camera
Show abstract
AMICA (Antarctic Medium Infrared Camera) [1] is the imaging camera that will support first-light testing for the IRAIT
telescope.
IRAIT (International Robotic Antarctic Infrared Telescope) is a 80 cm class telescope to be installed at Dome C, a site
located at 3200m height on the Antarctic plateau. AMICA, placed at the telescope Nasmyth focus, is a dual feed infrared
camera: a medium infrared optical beam designed to be operated by a Si:As detector array covering the range 5-28 μm,
and a near infrared optical beam operated by a In:Sb detector array covering the spectral range down to J band. A
specific goal of this project, having to face the prohibitive Antarctic environment imposing strong limits to human and
equipments operation, is the need to implement robotic and remotely controlled procedures for the telescope and its
instrumentation. This will impose well integrated and cooperative control systems, besides the accurate insulation for all
the equipment exposed to the extreme environmental conditions of Dome C (T -90, p 640 mbar).
In the present paper we will provide an overview of the progress so far obtained in the construction and testing of the
AMICA control system.
Detector upgrade for FLAMES: GIRAFFE gets red eyes
Show abstract
GIRAFFE is an intermediate resolution spectrograph covering a wavelength range from 360-930nm and fed by
optical fibers as a part of FLAMES, the multi-object fiber facility mounted at the ESO VLT Kueyen. For some time we sought a new detector for GIRAFFE spectrograph to boost the instrument's red QE (Quantum Efficiency) capabilities, while still retaining very good blue response. We aimed also at reducing the strong fringing present in the red spectra. The adopted solution was an e2v custom 2-layer AR (Anti-Reflection) coated Deep Depletion CCD44-82 CCD. This device was made in a new e2v Technologies AR coating plant and delivered to ESO in mid 2007 with performance that matches predictions. The new CCD was commissioned in May 2008. Here we report on the results.
Characterization and testing of FLAMINGOS-2: the Gemini facility near-infrared multi-object spectrometer and wide-field imager
Show abstract
FLAMINGOS-2 is a near-infrared wide-field imager and fully cryogenic multi-object spectrometer for Gemini
Observatory being built by the University of Florida. FLAMINGOS-2 can simultaneously carry 9 custom cryogenic
multi-object slit masks exchangeable without thermally cycling the entire instrument. Three selectable grisms provide
resolving powers which are ~1300 to ~3000 over the entire spectrograph bandpass of 0.9-2.5 microns. We present and
discuss characterization data for FLAMINGOS-2 including imaging throughput, image quality, spectral performance,
and noise performance. After a lengthy integration process, we expect that FLAMINGOS-2 will be in the midst of
commissioning at Gemini South by the fall of 2008.
SPHERE IFS: the spectro differential imager of the VLT for exoplanets search
Show abstract
SPHERE is an exo-solar planet imager, which goal is to detect giant exo-solar planets in the vicinity of bright stars and
to characterize them through spectroscopic and polarimetric observations. It is a complete system with a core made of an
extreme-Adaptive Optics (AO) turbulence correction, pupil tracker and interferential coronagraphs. At its back end, a
differential dual imaging camera and an integral field spectrograph (IFS) work in the Near Infrared (NIR) Y, J, H and Ks
bands (0.95 - 2.32μm) and a high resolution polarization camera covers the visible (0.6 - 0.9 μm). The IFS is a low
resolution spectrograph (R~50 and R~30) which works in the near IR (0.95-1.7 microns), an ideal wavelength range for
the detection of planetary features. In our baseline design the IFU is a new philosophy microlens array of about 145x145
elements designed to reduce as low as possible the contrast. The IFU will cover a field of view of about 1.8 x 1.8 square
arcsecs reaching a contrast of 10-7, giving an high contrast and high spatial resolution "imager" able to search for planet
well inside the star PSF.
SPHERE ZIMPOL: overview and performance simulation
Show abstract
The ESO planet finder instrument SPHERE will search for the polarimetric signature of the reflected light from
extrasolar planets, using a VLT telescope, an extreme AO system (SAXO), a stellar coronagraph, and an imaging
polarimeter (ZIMPOL). We present the design concept of the ZIMPOL instrument, a single-beam polarimeter
that achieves very high polarimetric accuracy using fast polarization modulation and demodulating CCD detectors.
Furthermore, we describe comprehensive performance simulations made with the CAOS problem-solving
environment. We conclude that direct detection of Jupiter-sized planets in close orbit around the brightest nearby
stars is achievable with imaging polarimetry, signal-switching calibration, and angular differential imaging.
SPHERE-IFS arm: a new concept of Nasmyth II generation instrumentation for ESO-VLT
Show abstract
Direct detection and spectral characterization of Extrasolar Planets is one of the most exciting but also one of the most
challenging areas in modern astronomy.
For the second-generation instrumentation on the VLT, ESO has supported the study and the design of instrument, called
SPHERE (Spectro-Polarimetric High-contrast Exoplanet Research). SPHERE includes a powerful extreme adaptive
optics system, various coronagraphs, an infrared differential imaging camera (IRDIS), an infrared Integral Field
Spectrograph (IFS) and a visible differential polarimeter (ZIMPOL).
IFS is a very low resolution spectrograph (R~50) which works in the near IR (0.95-1.7 microns), an ideal wavelength
range for the ground based detection of planetary features. The IFS requirements have been met via an innovative
integrated design merging passive stiffness and active control to obtain a light, accessible and functional assembly. This
paper gives a description of its cryogenic and mechatronic integrated design.
SPHERE IFS optical concept description and design overview
Show abstract
Integral field spectroscopy coupled with an extreme adaptive optics system and coronagraphy allows a marked
improvement of the standard spectroscopic simultaneous differential imaging calibration technique. Hence, with an
integral field spectrograph (IFS) direct imaging of extrasolar giant planets becomes potentially feasible over a wide
range of ages, masses, and separations from the hosting stars. This aim represents the prime goal of the planet finder
instrument for the VLT (SPHERE). Inside SPHERE, the IFS channel exploits various spectral features of the candidate
planets in the near infrared, in order to reduce the speckles noise at the level of the stellar background noise, over a field
of view comprised between the coronagraphic inner working angle and the outer working angle provided by the
SPHERE extreme adaptive optic system (SAXO). The IFS allows then to realize an extensive spectroscopic
simultaneous differential imaging calibration technique, and at least in few cases, to get the spectrum of the candidate
extrasolar giant planets. Here we present the IFS baseline design, which is based upon a new optical concept we
developed for its integral field unit (BIGRE). When applied to the technical specifications of SPHERE IFS, a BIGRE
integral field unit is able to take into account all the effects appearing when integral field spectroscopy is used in
diffraction limited conditions and for high-contrast imaging purposes. Finally a BIGRE-oriented IFS optical design is
shown here to reach the requested high optical quality by standard lenses-based optical devices.
Frame combination techniques for ultra-high-contrast imaging
Show abstract
We summarize here an experimental frame combination pipeline we developed for ultra high-contrast imaging with
systems like the upcoming VLT SPHERE instrument. The pipeline combines strategies from the Drizzle technique, the
Spitzer IRACproc package, and homegrown codes, to combine image sets that may include a rotating field of view and
arbitrary shifts between frames. The pipeline is meant to be robust at dealing with data that may contain non-ideal
effects like sub-pixel pointing errors, missing data points, non-symmetrical noise sources, arbitrary geometric distortions,
and rapidly changing point spread functions. We summarize in this document individual steps and strategies, as well as
results from preliminary tests and simulations.
Apodized Lyot coronagraph for VLT-SPHERE: laboratory tests and performances of a first prototype in the visible
Show abstract
We present some of the High Dynamic Range Imaging activities developed around the coronagraphic test-bench of the Laboratoire A. H. Fizeau (Nice).
They concern research and development of an Apodized Lyot Coronagraph (ALC) for the VLT-SPHERE instrument and experimental results from our testbed working in the visible domain.
We determined by numerical simulations the specifications of the apodizing filter
and searched the best technological process to manufacture it.
We present the results of the experimental tests on the first apodizer prototype in the visible and the resulting ALC nulling performances.
The tests concern particularly the apodizer characterization (average transmission radial profile, global reflectivity and transmittivity in the visible), ALC nulling performances compared with expectations, sensitivity of the ALC performances to misalignments of its components.
BIGRE: a new double microlens array for the integral field spectrograph of SPHERE
Show abstract
IFS is the Integral Field Spectrograph for SPHERE, a 2nd generation instrument for VLT devoted to the search of
exoplanets.
To achieve the performances required for the IFS a new device sampling the focal plane has been designed, prototyped
and tested in laboratory. This device named BIGRE consists of a system made of two microlens arrays with different
focal lengths and thickness equal to the sum of them and precisely aligned each other. Moreover a mask has been
deposited on the first array to produce a field stop for each lenslet. Laboratory tests confirmed that specifications and
properties of the prototype are met by state of the art on optics microlens manufacturing.
To characterize the device, a simulator of IFS has been built in laboratory and the BIGRE properties have been tested in
real working conditions, showing that the design of the double array fulfills IFS requirements.
The infra-red dual imaging and spectrograph for SPHERE: design and performance
Show abstract
The SPHERE (Spectro-Polarimetric High-contrast Exoplanet Research) planet finder instrument for ESO's VLT
telescope, scheduled for first light in 2011, aims to detect giant extra-solar planets in the vicinity of bright stars by the aid
of an extreme-AO turbulence compensation system and to characterize the objects found through spectroscopic and
polarimetric observations. Dual imaging observations within the Y, J, H and Ks atmospheric windows (~0.95 - 2.32μm)
will be done by the aid of the IRDIS cryogenic camera. We describe briefly the science goals of IRDIS and present its
system architecture. Current status of the instrument design is presented, and expected performance is described in terms
of end-to-end simulations.
Calibration and data reduction for planet detection with SPHERE-IFS
Show abstract
The 2nd generation VLT instrument SPHERE will include an integral field spectrograph to enhance the capabilities
of detection of planetary companions close to bright stars. SPHERE-IFS is foreseen to work in near
IR (0.95-1.65 micron) at low spectral resolution. This paper describes the observing strategies, the adopted
hardware solutions for calibrating the instrument, and the data reduction procedures that are mandatory for the
achievement of the extreme contrast performances for which the instrument is designed.
High efficiency near infrared spectrometer for zodiacal light spectral study
Show abstract
We are developing a near infrared spectrometer for measuring solar absorption lines in the zodiacal light in the
near infrared region. it has been recently demonstrated1 that observing single Fraunhofer line can be a powerful
tool for extracting zodiacal light parameters based on the measurements of the profile of the Mg I line at 5184 A.
We are extending this technique to the near infrared with the primary goal of measuring the absolute intensity of
the zodiacal light. This measurement will provide the crucial information needed to accurately subtract zodiacal
emission from the DIRBE (Diffuse Infrared Background Experiment) diffuse sky measurements to determine
the intensity of the extragalactic infrared background. The instrument design is based on a dual Fabry-Perot
interferometer with a narrow band filter. Its double etalon design allows to achieve high spectral contrast to
reject the bright out of band atmospheric hydroxyl emission. High spectral contrast is absolutely necessary to
achieve detection limits needed to accurately measure the intensity of the absorption line. We present the design,
the estimated performance of the instrument, and the expected results of the observing program.
KMOS housekeeping electronics and its functions
Show abstract
KMOS is a second generation near infrared multi-object spectrograph instrument for the VLT. It is a highly complex
astronomical instrument with over 60 cryo-mechanisms deploying pickoff arms, moving filter wheels and detector focus
stages. The instrument houses three identical sections each consisting of 8 pickoff arms, 2 filter wheels, 8 integral field
units feeding a spectrograph and its detector systems. The housekeeping electronics provides a semi-automation of the
cryostat functions such as pump down, cool down and warm up sequences, vacuum and temperature measurement and
control etc. The infrastructure electronics is responsible for the safe operation of the instrument. It monitors the various
cryostat conditions, takes automatic corrective actions under faulty conditions and raises alarms when a manual
intervention is needed. This semi-automation design is aimed at not only minimising the risk of instrument damage, but
also takes into account the safety of instrument manual handling. This paper describes the design of the instrument
infrastructure electronics and details its functions such as semi-automation of the cryostat procedures, housekeeping
diagnostics, automatic corrective actions under faulty conditions, scheme of alarm and warnings, detector thermal
protection etc. and presents the associated interfaces to the control electronics and the cable co-rotator.
Airborne measurements in the longwave infrared using an imaging hyperspectral sensor
Show abstract
Emerging applications in Defense and Security require sensors with state-of-the-art sensitivity and capabilities. Among
these sensors, the imaging spectrometer is an instrument yielding a large amount of rich information about the measured
scene. Standoff detection, identification and quantification of chemicals in the gaseous state is one important
application. Analysis of the surface emissivity as a means to classify ground properties and usage is another one.
Imaging spectrometers have unmatched capabilities to meet the requirements of these applications.
Telops has developed the FIRST, a LWIR hyperspectral imager. The FIRST is based on the Fourier Transform
technology yielding high spectral resolution and enabling high accuracy radiometric calibration. The FIRST, a man
portable sensor, provides datacubes of up to 320×256 pixels at 0.35mrad spatial resolution over the 8-12 μm spectral
range at spectral resolutions of up to 0.25cm-1. The FIRST has been used in several field campaigns, including the
demonstration of standoff chemical agent detection [http://dx.doi.org/10.1117/12.788027.1]. More recently, an airborne
system integrating the FIRST has been developed to provide airborne hyperspectral measurement capabilities. The
airborne system and its capabilities are presented in this paper.
The FIRST sensor modularity enables operation in various configurations such as tripod-mounted and airborne. In the
airborne configuration, the FIRST can be operated in push-broom mode, or in staring mode with image motion
compensation. This paper focuses on the airborne operation of the FIRST sensor.
AAOmicron: a wide-field near-infrared multi-object spectrograph concept for the AAT
Show abstract
AAOmicron is a wide-field, fiber-fed, multi-object, near-infrared spectrograph concept for the Anglo Australian
Telescope (AAT). It is one of a number of instruments concepts (primarily for bright time use) recently considered to
complement the existing instrumentation and in particular the highly popular AAOmega system (primarily dark and grey
time usage). AAOmicron has a two-degree field of view, 240 robotically configured fibers and operates between 0.98
and 1.75μm at a resolution of R~3500. AAOmicron offers a broad suite of applications from the study of low-mass stars,
to determining the structure of the high-redshift Universe. We present an overview of the instrument concept, which is
based heavily on the highly successful AAOmega system, and describe how the AAOmega spectrograph design could be
adapted for near-infrared observations to provide a highly cost effective and scientifically compelling instrument.
LUCIFER status report: summer 2008
Show abstract
LUCIFER is a NIR spectrograph and imager (wavelength range 0.9 to 2.5 micron) for the Large Binocular
Telescope (LBT) on Mt. Graham, Arizona, working at cryogenic temperatures of less than 70K. Two instruments
are built by a consortium of five German institutes and will be mounted at the bent Gregorian foci of the two
individual telescope mirrors. Three exchangable cameras are available for imaging and spectroscopy: two of
them are optimized for seeing-limited conditions, a third camera for the diffraction limited case will be used with
the LBT adaptive secondary mirror working. Up to 33 exchangeable masks are available for longslit or multi-object
spectroscopy (MOS) over the full field of view (FOV). Both MOS-units (LUCIFER 1 and LUCIFER
2) and the auxiliary cryostats together with the control electronics have been completed. The observational
software-package is in its final stage of preparation.
After the total integration of LUCIFER 1 extensive tests were done for all electro-mechanical functions and
the verification of the instrument started. The results of the tests are presented in detail and are compared with
the specifications.
Performances of the cryogenic system of GIANO-TNG
Show abstract
GIANO-TNG is a cryogenic high resolution infrared spectrometer whose optics include large aspheric mirrors
and cross-dispersing prisms mounted over a ≃1.5 m2 aluminum bench. To achieve the highest possible spectral
stability and repeatability the bench is internally filled with liquid nitrogen whose boil-off pressure is actively
controlled and stabilized to a fraction of mbar. The bench is isostatically mounted inside a ≃2.5 m3 cryostat.
We present the characteristics and performances of the cryogenic system of GIANO which include, in particular,
a temperature uniformity and long-term stability of a few mK and a remarkably low consumption of liquid
nitrogen (less than 1 liter/hr).
Characterization of the HCl-HBr-HI gas absorption cell for GIANO-TNG
Show abstract
GIANO is an high resolution cross-dispersed spectrometer operating at near IR wavelengths (0.9-2.5 microns) which will
be soon commissioned at the 3.6m TNG Italian telescope in La Palma. One of its most ambitious aims is searching for
earth-like planets with habitable conditions around very cool main sequence stars. This requires measurements of radial
velocities with accuracies of a few m/s which can be achieved by means of a gas absorption cell containing a mixture of
the halogen-hydrates HCl, HBr and HI. We present here the results of the laboratory work for the construction and
characterization of such cell.
Integration, commissioning, and performance of the UK FMOS spectrograph
Show abstract
The UK FMOS spectrograph forms part of Subaru's FMOS multi-object infrared spectroscopy facility. The spectrograph
was shipped to Hilo in component form in August of 2007. We describe the integration sequence for the spectrograph,
the results of cooldown tests using a new chiller unit fitted to the spectrograph at the telescope, and alignment tests of the
spectrograph, gratings and OH-suppression masks. We present the first-light observations for the spectrograph from May
2008.
X-shooter physical model
Show abstract
We have developed a physical model of the VLT 2nd generation instrument X-shooter for use in wavelength
calibration. We describe here the model concept, its use during the development of the data reduction software
and the initial alignment of the spectrograph in the laboratory and the optimisation of the model to fit early
laboratory data.
Wavelength calibration sources for the near infrared arm of X-shooter
Show abstract
We have studied the properties of wavelength calibration sources for the near-IR (NIR: 1000-2500 nm) arm of X-shooter.
In a novel approach we are combining laboratory measurements from a Fourier Transform Spectrometer (FTS)
and literature data with corresponding simulated data derived from a physical model of X-shooter. The sources studied
are pen ray lamps filled with the noble gases Ne, Ar, Kr, and Xe and Th-Ar hollow cathode lamps. As a product we
provide a quantitative order by order analysis of the expected properties of the calibration lamps during X-shooter
operations. The analysis accounts for blending of lines and makes realistic assumptions about the dynamic range
available in a typical wavelength calibration exposure. Based on our study we recommend the use of Ne, Kr, and Ar as
the best three lamp combination for X-shooter calibration. A detailed comparison between the predicted and actual
performance of the calibration system has been started as part of the X-shooter testing and validation phase and first
results are very promising. To our knowledge this is the first time that such a detailed and quantitative analysis of a
calibration system has been done prior to the operation of the instrument. The combination of laboratory measurements
and instrument modeling provides a powerful tool for future instrument development.
X-shooter-backbone and UV-blue and visible spectrographs: final AIV and measured performances
Show abstract
X-shooter is a wide band (U to K) intermediate resolution (4000-14000) single object three-arms spectrograph for
the VLT. Currently in the last phase of integration, X-shooter will see the first light at ESO Paranal as the first of the
VLT second generation instruments in the last quarter of 2008. We describe in this paper the final steps in the
integration and testing phase of the central Backbone with its key functions (including the active flexure
compensation mirrors) and of the two UV-Blue and Visible spectroscopic arms. We report on the stability results of
the preslit optics and of the spectrographs and on the remarkable efficiency which is derived from the measurements
of the optical components of the instrument.
A new measurement method of profile tolerance for the LAMOST focal plane
Show abstract
There were a few methods taken in the profile tolerance measurement of the LAMOST Focal Plane Plate. One of the
methods was to use CMM (Coordinate Measurement Machine) to measure the points on the small Focal Plane Plate and
calculate the points whether or not in the tolerance zone. In this process there are some small shortcomings. The
measuring point positions on the Focal Plane Plate are not the actual installation location of the optical fiber positioning
system. In order to eliminate these principle errors, a measuring mandrel is inserted into the unit-holes, and the precision
for the mandrel with the hole is controlled in the high level. Then measure the center of the precise target ball which is
placed on the measuring mandrel by CMM. At last, fit a sphere surface with the measuring center points of the target ball
and analyze the profile tolerance of the Focal Plane Plate. This process will be more in line with the actual installation
location of the optical fiber positioning system. When use this method to judge the profile tolerance can provide the
reference date for maintaining the ultra error unit-holes on the Focal Plane Plate. But when insert the measuring mandrel
into the unit hole, there are manufacturing errors in the measuring mandrel, target ball and assembly errors. All these
errors will bring the influence in the measurement. In the paper, an impact evaluation assesses the intermediate process
with all these errors through experiments. And the experiment results show that there are little influence when use the
target ball and the measuring mandrel in the measurement of the profile tolerance. Instead, there are more advantages
than many past use of measuring methods.
Study on measurement error of fiber space coordinate detection using an area CCD camera for the LAMOST positioning system
Show abstract
An area CCD camera is used to detect space coordinates of fibers in LAMOST positioning system, which is
National Ninth Five Great Scientific Project, in order to achieve the detection of real-time, un-touched and high
accuracy. This measurement method is based on photogrammetry and is applied in many other photometric
measurement systems. The positioning accuracy for LAMOST is less than 40m, so fibers' position detection
accuracy is at least one-third of it. The position detection of static goals through general photogrammetry can
achieve high accuracy, about several microns. But fibers are active in LAMOST, so the systematic research
about CCD measurement under this circumstance is carried on in this paper, which includes measurement
error magnitude, form of expression, influencing factors, causes and ways to reduce measurement error. Some
conclusions can be obtained through position detection experiments for movement fibers: The measurement
method with a CCD camera for position detection has a good measurement stability, its accuracy can achieve
about 2 microns for 8 hours; This method also has a high accuracy for position detection of one-dimensional
movement fibers, which is less than 5 microns within the movement distance of several millimeters; But when
fibers move in a curtain space freely, F number, lamp-house, speckle status and imaging size will probably cause
additional measurement error. It is about a dozen microns to tens of microns and it stems from the changes of
light intensity distribution of imaging speckles while fibers are moving. Finally, it is discussed simply to improve
the measurement method and reduce measurement error.
The testing scheme for the LAMOST focal plane plate
Show abstract
At present, the LAMOST project is in a crucial period. The machining progressing of LAMOST Focal Plane Plate has
completed. The inspection of the machining quality for the Focal Plane Plate in the machining process is a pivotal work.
In all of the design requirements, the most crucial standards of accuracy are the profile tolerance and the unit-holes
dimensional angle. Theirs precision will influence the observation efficiency of the LAMOST. But there are more than
4000 unit-holes on the 1.75m diameter Focal Plane Plate, it is impossible to measure all unit-holes and the whole area of
the Focal Plane Plate. How to measure the minimal unit-hole and get the most accurate results about the machining
process, judge whether the final machining Focal Plane Plate satisfy the design requirements. The measurement scheme
optimization is discussed in the paper. There are two different ways to measure the Focal Plane Plate, one is the
traditional way whish use specially designed implements for the every individual parameter, the other way used the
CMM to measure the pivotal design requirements such as unit-hole dimensional angle and the profile tolerance of the
Focal Plane Plate. The advantage of this is saving the time and cost on the CMM, improving the efficiency for the whole
measurement work, and acquires the direct vision results before measuring the Focal Plane Plate on CMM. Whereas the
implement which used in the measurement need to design and machine precisely for the credible measurement results.
And all the measuring work is calibrated by the CMM sampling detection. The sampling detection based on the
processing technology and some implements are mentioned in the paper.
Flat field for LAMOST
Show abstract
Large sky area multi-object spectroscopic telescope(LAMOST) is a reflecting schmidt telescope, the unique
telescope structure make it compatible with both large sky area and large aperture. While the vignetting effect
of the telescope is not the same everywhere, the flat field is quite different from the common flat field which use a
lamp projecting to a fixed white screen. We describe the Schmidt reflector(MA) cover solution of the LAMOST
flat field, simulation shows the variation across the field of view is less than 2 percent. The material of flat field
screen is carefully chosen to have both high reflectivity and diffusion. We also describe the material test for the
LAMOST flat field screen. Flat field lamp should have high color temperature to raise the sinal in the shorter
wavelength. The possible solution for the flat field lamp is described.
A new method for measuring the position of the end of optical fibers for LAMOST
Show abstract
Measuring the position of the end of 4000 optical fibers on the spherical focal plate for the LAMOST (Large Sky Area
Multi-Object Fiber Spectroscopy Telescope) optical fibers positioning system is one of the key problems for LAMOST.
Currently, the area CCD camera is used to measure the positions conveniently and quickly. However, due to too small
size of area CCD, the large-size focal plate should be reduced large multiples to image on the area CCD, and in this
process, there is error amplification which will disturb the improvement of measuring precision. So far, the precision of
this method does not meet the requirement. Therefore, a new method with linear CCD sensors is created. The device
consists of a rotary encoder and a scanning frame on which several linear CCD sensors are spliced into a measuring
baseline. The scanning frame can be driven by step motor and take a slow rotation around the center axis of the focal
plate and close to the surface of the focal plate. In the course of rotation, each time the scanning frame turns a very small
angle, the linear CCD sensors take an acquisition and get the radial coordinate of the end of optical fibers, the rotary
encoder records the angle coordinate, and this polar coordinates can be used to express the position of the end of optical
fibers. This new method is a 1:1 measurement, and it hasn't error amplification but has high precision in theory. The
main content of this paper is to build the measuring model of the new method with linear CCD.
MicroLux: high-precision timing of high-speed photometric observations
Show abstract
MicroLux is a GPS-based high precision and high speed timing add-on to the Calar Alto Lucky Imaging camera
AstraLux. It allows timestamping of individual CCD exposures at frame rates of more than 1 kHz with an
accuracy better than one microsecond with respect to the UTC timeframe. The system was successfully used
for high speed observations of the optical pulse profile of the Crab pulsar in January and November 2007. I
present the technical design concept of MicroLux as well as first results from these observations, in particular
the reconstructed pulse profile of the pulsar.
FastCam: a new lucky imaging instrument for medium-sized telescopes
Show abstract
FastCam is an instrument jointly developed by the Spanish Instituto de Astrofísica de Canarias and the Universidad Politécnica de Cartagena designed to obtain high spatial resolution images in the optical wavelength range from ground-based telescopes.
The instrument consists of a very low noise and very fast readout speed EMCCD camera capable of reaching the diffraction limit of medium-sized telescopes from 500 to 850 nm. FastCam incorporates a FPGAs-based device to save and evaluate those images minimally disturbed by atmospheric turbulence in real time. The undisturbed images represent a small fraction of the observations. Therefore, a special software package has been developed to extract, from cubes of tens of thousands of images, those with better quality than a given level. This is done in parallel with the data acquisition at the telescope.
After the first tests in the laboratory, FastCam has been successfully tested in three telescopes: the 1.52-meter TCS (Teide Observatory), the 2.5-meter NOT, and the 4.2-meter WHT (Roque de los Muchachos Observatory). The theoretical diffraction limit of each telescope has been reached in the I band (850 nm) -0.15, 0.08 and 0.05 arcsec, respectively-, and similar resolutions have been also obtained in the V and R bands.
Future work will include the development of a new instrument for the 10.4-meter GTC telescope on La Palma.
AstraLux: the Calar Alto lucky imaging camera
Show abstract
AstraLux is the Lucky Imaging camera for the Calar Alto 2.2-m telescope, based on an electron-multiplying
high speed CCD. By selecting only the best 1-10% of several thousand short exposure frames, AstraLux provides
nearly diffraction limited imaging capabilities in the SDSS i' and z' filters over a field of view of 24×24 arcseconds.
By choosing commercially available components wherever possible, the instrument could be built in short time
and at comparably low cost. We present the instrument design, the data reduction pipeline, and summarise the
performance and characteristics.
Real-time lucky imaging in FastCam project
Show abstract
Lucky imaging techniques implemented by the FastCam group (see http://www.iac.es/proyecto/fastcam/) at the Instituto
de Astrofisica de Canarias have demonstrated its ability to obtain spectacular diffraction limited images in telescopes
ranging from 1 to 4.2 m in visible wavelengths (mainly in the I band), at the expense of using only a small percentage of
the available images. This work presents the development of a real-time processor, FPGA-based, capable of performing
all the required processing involved in the lucky imaging technique: Bias and flat-field correction, quality evaluation of
images, quality threshold for image selection, image recentering and accumulation, and finally sending through Gigabit
Ethernet both raw and processed images to a PC computer. Furthermore, a real time display is generated directly from
FPGA showing both types of images, plus a histogram of the computed quality values and the threshold used. All
processes can co-exist physically located in separated places inside the FPGA, using its natural parallel approach, and
can easily handle the 512x512 pixels at 30 fps found at the sensor camera output (an Andor Ixon+ DU-897ECSO
EMCCD). Flexibility and parallel processing features of the reconfigurable logic have been used to implement a novel
imaging strategy for segmented-mirror telescopes, allowing separate evaluation of every segment and posterior
accumulation to achieve the resolution limit of a single segment with the integration capability of the full primary mirror.
The shutter and filter exchanger system of Hyper Suprime-Cam
Show abstract
The next generation wide field camera HSC (Hyper Suprime-Cam) on Subaru telescope is planned to
cover 1.5 degree diameter field with a focal plane size about 650mm. To minimize the impact to the telescope,
the design for the elements of the camera is constraint to the tight space and weight limits. In order to fit the
available space, the screen winding shutter and petal shape filter exchanger are designed for the HSC. The
CFRP is used for the structure to minimize the load. In this report, the design and analysis for the shutter and
filter exchanger system will be presented. The result for the shutter membrane tests will also be discussed.
EDiFiSE: equalized and diffraction-limited field spectrograph experiment
Show abstract
We present EDiFiSE, a prototype instrument for the observation of high-contrast systems, combining an adaptive
optics (AO) system and an equalized integral field unit (EIFU). The design of the AO system takes into account
the statistical behaviour of the atmospheric turbulence structure at the Canary Islands (Spain) astronomical
observatories: Roque de los Muchachos (ORM) on the island of La Palma and Teide observatory (OT) in
Tenerife. The AO will have the capability of adapting to the prevailing turbulence conditions; in this sense,
the EDiFiSE AO unit will be an 'adaptable' adaptive optics system. The corrected beam feeds an hexagonal
integral field unit formed by 331 micro-lenslets, which focus the intensity distribution at the focal plane into 331
optical fibers. The central seven fibers of the bundle include variable attenuators for the equalization of these
fibers output intensities, matching them to the dynamical range of the detector and reducing the optical cross
talk inside the spectrograph. This technique, called equalized integral field spectroscopy (Arribas, Mediavilla &
Fuensalida 19981), permits to obtain spectral and spatial information of the equalized object and its surroundings
as well as accurate relative photometry and astrometry.
Testing commercial variable fiber attenuators and lenslet arrays for equalized integral field spectroscopy applications
Show abstract
We have been testing at laboratory commercial variable attenuators commonly used in telecommunication applications
for their used in astronomy. Such variable attenuators are going to be included in the central fibers
of the integral field unit (IFU) of the prototype instrument EDiFiSE (Equalized and Diffraction-limited Field
Spectrograph Experiment). The EDiFiSE IFU is conformed by a lenslet array of 331 lenses, 331 fibers and seven
variable attenuators (inserted in the seven central fibers of the bundle). We present here the characterization of
the attenuator devices tested for their use in astronomy and, in particular, to their application in the observation
of object of large dynamic range using equalized integral field spectroscopy. We also present the optical tests we
have carried out to characterize the performances of two lenslet arrays acquired in the framework of the EDiFiSE
project.
Multi-object medium resolution optical spectroscopy at the E-ELT
Show abstract
We present the design of a compact medium resolution spectrograph (R~15,000-20,000), intended to operate on a 42m
telescope in seeing-limited mode. Our design takes full advantage of some new technology optical components, like
volume phase holographic (VPH) gratings. At variance with the choice of complex large echelle spectrographs, which
have been the standard on 8m class telescopes, we selected an efficient VPH spectrograph with a limited beam diameter,
in order to keep overall dimensions and costs low, using proven available technologies. To obtain such a resolution, we
need to moderately slice the telescope image plane onto the spectrograph entrance slit (5-6 slices). Then, standard
telescope AO-mode (GLAO, Ground Layer Adaptive Optics) can be used over a large field of view (~10 arcmin),
without loosing efficiency. Multiplex capabilities can greatly increase the observing efficiency. A robotic pick-up mirror
system can be implemented, within conventional environmental conditions (temperature, pressure, gravity, size),
demanding only standard mechanical and optical tolerances. A modular approach allows us scaling multiplex capabilities
on overall costs and available space.
A novel design of a fibre-fed high-resolution spectrograph for WFMOS
Show abstract
We present a novel design of a fibre-fed high-resolution spectrograph (HRS hereafter) for WFMOS. WFMOS
HRS is a multi-object spectrograph for studying the formation and evolution history of our Galaxy by measuring
spectra of Galactic stars. In a 8m-class telescope, it aims to measure 1,500 stellar spectra simultaneously with
spectral resolution between 25,000 and 40,000 in optical wavebands defined within 4000Å and 9000Å. For the
HRS optical design, we have explored three disperser options: Volume Phase Holographic Grating (VPHGs),
prism-immersed VPHG, and Echelle grating. Two camera designs have also been studied for the spectrograph
camera optics, one tranmissive design and the other a Schmidt design. We also investigated a conjugate collimator
design that allows two spectrographs to share a single grating so as to work as a single spectrograph.
SIDE: a fiber fed spectrograph for the 10.4 m Gran Telescopio Canarias (GTC)
Show abstract
SIDE (Super Ifu Deployable Experiment) will be a second-generation,common-user instrument for the Grantecan (GTC)
on La Palma (Canary Islands, Spain). It is being proposed as a spectrograph of low and intermediate resolution, highly
efficient in multi-object spectroscopy and 3D spectroscopy. SIDE will feature the unique possibility of performing
simultaneous visible and IR observations for selected ranges. The SIDE project is leaded by the Instituto de Astrofsica de
Andaluca in Granada (Spain) and the SIDE Consortium is formed by a total of 10 institutions from Spain, Mexico and
USA. The feasibility study has been completed and currently the project is under revision by the GTC project office.
PRL advanced radial-velocity all-sky search (PARAS): an efficient fiber-fed spectrograph for planet searches
Show abstract
We present here the optical design of an efficient Fiber-fed, Prism Cross-dispersed, Echelle Spectrograph (Resolution
~70,000 @seeing limited ~2arcsecs conditions) which will operate in the wavelength region of 3700A to 8100A. It will
be used for extra-solar planets searches down to the precision of 3m/s and as well as for follow-up observations for new
transit discoveries. The spectrograph design is such that with a beam size of 100mm (4inch) it should suit the existing 1
to 2m class of telescopes available in India. The fiber-fed spectrograph will be installed with a 1.2m telescope, which is
situated at Mt. Abu (5800feet), Rajasthan, India. We estimate the spectrograph to be >30% efficient from the slit to the
CCD detector, and up to 15% efficient including sky, telescope, fiber-fed optics etc. We expect to reach the S/N ratio of
70 on a 10mag star for an integration time of 40mins. We aim to achieve 5m/s to 3m/s Radial Velocity accuracies on
such a star using the simultaneous ThAr referencing method. Since thermal stability is absolutely necessary to achieve
<5m/s RV accuracies, the whole spectrograph is planned to be kept inside a vibration free isolated tank under low
vacuum (0.001 mbar) in a thermally isolated room at 28C +/- 0.01C. It should see the first light by the summer of 2009.
We are guaranteed at least 120 nights per year for the planet search program, more nights are possible.
BESO: first light at the high-resolution spectrograph for the Hexapod-Telescope
Show abstract
BESO (Bochum Echelle Spectrograph for OCA)is a high-resolution echelle spectrograph which has been built by Ruhr-Universitaet, Bochum and Landessternwarte Heidelberg. It is fiber-coupled to the 1.5m Hexapod-Telescope at the Observatario Cerro Armazones (OCA), Chile. The first light spectra show that the resolution of 48.000 over a spectral range from 370 nm to 840 nm has been achieved. An alignment by design approach has been followed to assemble the fiber-head optics at the telescope side of fiber coupled instrument.
Coupling LBT's double pupil into optical fibers
Show abstract
In the context of interferometric integral field spectroscopy at the LBT, we have investigated the physics of coupling
light from a double pupil into optical fibers. Previous fiber-fed astronomical instruments solved the problem of coupling
light from a single dish into single- and multi-mode fibers. However, this is an unexplored territory for a telescope
configuration such as the LBT. We have investigated the coupling of the telescope's double pupil to optical fibers in
detail, and present results from numerical simulations and preliminary measurements from an experimental setup.
Concepts for a high-resolution multi-object spectrograph for galactic archeology on the Anglo-Australian Telescope
Show abstract
Mapping out stellar families to trace the evolutionary star formation history of the Milky Way requires a spectroscopic facility able to deliver high spectral resolution (R≥30k) with both good wavelength coverage (~400 Ang) and target multiplex advantage (~400 per 2 degree field). Such a facility can survey 1,200,000 bright stars over 10,000 square degrees in about 400 nights with a 4-meter aperture telescope. Presented are the results of a conceptual design study for such a spectrograph, which is under development as the next major instrument for the Anglo-Australian Observatory. The current design (that builds upon the AAOmega system) makes use of a White Pupil collimator and an R3 echelle that is matched to the existing AAOmega cameras. The fibre slit can be reconfigured to illuminate the Pupil relay side of the collimator mirror bypassing the echelle, thus preserving the lower dispersion modes of the AAOmega spectrograph. Other spectrograph options initially considered include use of an anamorphic collimator that reduces the required dispersion to that achievable with VPH grating technology or possible use of a double-pass VPH grating.
2dF grows up: Echidna for the AAT
Show abstract
We present the concept design of a new fibre positioner and spectrograph system for the Anglo-Australian Telescope,
as a proposed enhancement to the Anglo-Australian Observatory's well-known 2dF facility. A four-fold multiplex
enhancement is accomplished by replacing the 400-fibre 2dF fibre positioning robot with a 1600-fibre Echidna unit,
feeding three clones of the AAOmega optical spectrograph. Such a facility has the capability of a redshift 1 survey of a
large fraction of the southern sky, collecting five to ten thousand spectra per night for a million-galaxy survey.
Wide-field one-shot optical polarimeter: HOWPol
Show abstract
For prompt optical polarimetry of gamma-ray burst (GRB) afterglow, we require wide-field imaging polarimeter which can produce both Stokes Q and U parameters from only a single exposure, as well as quickly-moving telescope and enclosure system. HOWPol is an optical imaging polarimeter which provides four
linearly polarized images at position angles of 0°,
45°, 90° and 135°, i.e., Stokes I, Q, U,
simultaneously.
The key device is the wedged double Wollaston prism described by
Oliva (1997)1 and Pernechele et al. (2003).2
The images are focused on two 2k×4k fully depleted CCDs.
We report the design and development of the optical devices of
HOWPol, which will be mounted to the 1.5-m Kanata telescope at
Hiroshima University and stand by the GRB alert.
Long slit spectroscopy for exoplanet characterization in SPHERE
Show abstract
Extrasolar planet observation and characterization is a major objective for astronomy in the coming decade. The
Spectro-Polarimetric High contrast imager for Exoplanets Research (SPHERE) instrument for the Very Large
Telescope (VLT) is currently under development to achieve this objective with greater performances than any
existing instruments. It will have the capability to observe planets down to few masses of Jupiter at separations as
small as 0.1 arcseconds from the central star thanks to dedicated extreme adaptive optics system and coronagraph.
Planets characterization will be achieved with IRDIS, one of the 3 science modules of SPHERE, using its long slit
spectroscopy (LSS) mode along with a Lyot coronagraph at low (~40) or medium (~400) resolution. Similarly to
the dual-band imaging (DBI) technique dedicated to detection, the main limitation of the long slit spectroscopy
is the speckles generated by instrumental static and quasi-static aberrations, especially when observing very close
to the star. Another performance limitation is the chromatic dependence of the speckles in the field, known as
speckle chromatism, which creates a modulation of the spectrum. Finally, we are also facing problems related
to long slit spectroscopy, such as slit efficiency, thermal background and difficulty to preserve the spectrum
continuum. Intensive simulations have been performed using the CAOS framework under IDL, in order to
simulate realistic spectra in terms of signal, noise and instrumental artifacts. We present here in details the
expected performances among with a detailed analysis of the various noise sources contributions. This analysis
leads to a quantitative estimation of the characterization limitations and optimized data reduction procedures.
Proposed instrumentation for PILOT
Show abstract
PILOT (the Pathfinder for an International Large Optical Telescope) is a proposed Australian/European optical/infrared
telescope for Dome C on the Antarctic Plateau, with target first light in 2012. The proposed telescope is 2.4m diameter,
with overall focal ratio f/10, and a 1 degree field-of-view. In median seeing conditions, it delivers 0.3" FWHM wide-field
image quality, from 0.7-2.5 microns. In the best quartile of conditions, it delivers diffraction-limited imaging down
to 1 micron, or even less with lucky imaging. The areas where PILOT offers the greatest advantages are (a) very high
resolution optical imaging, (b) high resolution wide-field optical imaging, and (c) all wide-field thermal infrared
imaging. The proposed first generation instrumentation consists of (a) a fast, low-noise camera for diffraction-limited
optical lucky imaging; (b) a gigapixel optical camera for
seeing-limited imaging over a 1 degree field; (c) a 4K x 4K
near-infrared (1-5 micron) camera with both wide-field and diffraction-limited modes; and (d) a double-beamed midinfrared
(7-40 micron) camera.
Verification and acceptance tests of the PRIMA DDL optics
Show abstract
The last step in designing and building instruments are the verification and acceptance tests of the assembled units and of
the final instrument. For instruments, which are engineered to work at the limit of feasibility, these tests must be accurate
and stable at a level much better than the expected performance of the instrument. Particularly for interferometric
instruments, this requires special care for the test planning and implementation in order to achieve the necessary
performance. This paper describes the verification and acceptance tests of the PRIMA DDL optics in terms of wavefront
error and tilt requirements as well as the assembling and aligning accuracy. We demonstrate the conformity of the optics
and point out the limitations of the test methods.
The WIYN One Degree Imager: an update
Show abstract
The WIYN Consortium is building the One Degree Imager (ODI) for its 3.5m telescope, located at Kitt Peak, Arizona
(USA). ODI will utilize both the excellent image quality and the one degree field of view of the WIYN telescope. Image
quality will be actively improved by localised tip/tilt image motion stabilisation using a novel concept of Orthogonal
Transfer Array (OTA) CCDs, which are a new detector type jointly developed with the PanSTARRS project. Its anticipated
median image quality of ≤ 0.55" in the R band will make ODI a unique and competitive instrument in the landscape of the
next generation of large field imagers.
A conceptual design of ODI was presented earlier at SPIE.1 In the meantime, this concept matured, the ODI project has
been fully funded, and it has entered the construction phase. A prototype camera (QUOTA) with a field of view of 16'x16'
has already seen first star light in fall 2006. In this paper we report on the evolution of ODI's definition, the design of its
components, the status of the OTA detector development, and the path towards first light in early 2010. In accompanying
papers we detail the design of the ODI's optical corrector, the mechanical structures, and the software & instrument system
control design.
Mechanical design of the WIYN One Degree Imager (ODI)
Show abstract
The WIYN consortium is building the One Degree Imager (ODI) to be mounted to a Nasmyth port of the WIYN 3.5m
telescope, located at Kitt Peak, Arizona (USA). ODI will utilize both the excellent image quality and the one-degree
field of view that the telescope delivers. To accommodate the large field of view (~0.39m diameter unvignetted field
with 0.54m across the diagonal of the one-degree-square, partially vignetted field), 0.6m-class optics are required. The
ODI design consists of a two element corrector: one serves as a vacuum barrier to the cryostat, the other is an asphere;
two independently rotating bonded prism pairs for atmospheric dispersion compensation (ADC); nine independently
deployable filters via a simple pivoting motion; and a 971 mega-pixel focal plane consisting of 64 orthogonal transfer
array (OTA) devices.
This paper is an overview of the mechanical design of ODI and describes the optical element mounting and alignment
strategy, the ADC & filter mechanisms, plus the focal plane. Additionally, the project status will be discussed.
In accompanying papers Jacoby1 describes ODI's optical design, Yeatts2 describes the software and control system
design, and Harbeck3 gives a general update on the project.
The WIYN One Degree Imager optical design
Show abstract
The main advantage of the WIYN One Degree Imager (ODI) over other wide-field imagers will be its exceptional image quality. The fine pixel scale (0.11") provides uncompromised sampling of stellar PSFs under most conditions (seeing >0.3"). The telescope routinely delivers the site seeing (median ~ 0.7") which is often below 0.5" FWHM, and can be as low as 0.25". The ODI specifications require the optics to maintain native high quality images. A two-element, fused silica, corrector meets the geometric error budget of 0.10" images, but the first element requires a mildly aspheric surface. The other element serves as the dewar window. A pair of cemented prisms (fused silica plus PBL6Y) serve as an ADC, which is essential to meet the image quality requirements for many observing programs. We describe the optical design details and its performance, the tolerances required, and the trade-offs considered for anti-reflection coatings. This paper is an update to a preliminary three-element design.
The Large Binocular Camera: description and performances of the first binocular imager
Show abstract
Since the very beginning of 2008, the Large Binocular Telescope (LBT) is officially equipped with it's first binocular
instrument ready for science observations: the Large Binocular Camera (LBC). This is a double CCD imager, installed at
the prime focus stations of the two 8.4m telescopes of LBT, able to obtain deep and wide field images in the whole
optical spectrum from UV to NIR wavelengths.
We present here the overall architecture of the instrument, a brief hardware review of the two imagers and notes how
observations are carried on. At the end we report preliminary results on the performances of the instrument along with
some images obtained during the first months of observations in binocular mode.
LBT report activities concerning the optomechanics alignment of the Large Binocular Camera's Red Channel
Show abstract
In this article activities on the Optomechanics of the Prime Focus Red Channel alignment are described from the moment
in which the instrument left Italy to be shipped to LBT site to the moment in which it has been successfully placed on the
second LBT arm. An overview is given, starting from the realization of a "clean laboratory" at LBT, going through the
alignment check and finally with the mounting operations of the instrument at the telescope and its alignment with the
"second eye" primary mirror, with tolerances good enough to perform the fine alignment on the sky with the telescope
Active Optics.
Hyper Suprime-Cam: camera dewar
Show abstract
We summarize the design of the camera dewar for Hyper Suprime-Cam (HSC) which is the next generation prime
focus camera for the Subaru Telescope. The camera dewar consists of six main components; base flange, focal
plane assembly, window assembly, wall assembly, front-end electronics asembly and back assembly. It is about 700
mm in diameter and 500 mm in height, accommodating 116 2k×4k full depletion type CCDs inside. The CCD
packages, whose heights are accurately controlled (P-V ~ 25μm), are installed on a silicon-carbide cold plate of 10 μm
flatness to ensure that the surface of CCDs is flat within the focal depth of the wide-field corrector (~ 34μm).
The cold plate is supported rigidly and thermally isolated by support posts which are made of Zirconia. We
carried out the deformation analysis and the thermal analysis of the dewar based on the finite-element analysis,
and demonstrate that the design is feasible. We also show the assembly sequence of the dewar.
Hyper Suprime-Cam: autoguider and Shack-Hartmann systems
Show abstract
We present methodology of the autoguider (AG) and Shack-Hartmann (SH) sensing systems which will be used for a wide-field camera, Hyper Suprime-Cam (HSC), on the prime focus of the Subaru 8.2-m telescope. For both systems, stellar images are formed on the HSC science CCDs. Although light from AG stars must pass
through bandpass filters, we can obtain enough photons for AG stars brighter than mAB < 14 mag in any bandpass filter assumed in order to achieve accurate autoguiding. Spatial number density of such bright stars from the SDSS database requires an area
of about two 2k×4k CCDs for AG stars. The optics of SH system except for the imaging CCDs is located within the HSC filter unit.
Hyper Suprime-Cam: CCD readout electronics
Show abstract
Hyper Suprime-Cam is planned to employ about 120 2k×4k fully-depleted CCDs with 4 signal outputs for each. The
data size of an image becomes larger than 2Gbytes. All of the CCDs are designed to be readout parallel within 20
seconds, and the readout noise is expected to be 5e. The frontend electronics will be mounted in a vacuumed cryostat,
and connected to the backend electronics mounted on the outside of the cryostat. The frontend electronics includes entire
analog circuits for CCD including CCD drivers, preamplifiers and ADC. The backend electronics consists of newly
developed gigabit Ethernet modules combined with 2Gbytes memory modules, and several supporting boards. We will
present the current status of the CCD readout electronics developments for HSC.
The 12Kx8K CCD mosaic camera for the Palomar Transient Factory
Show abstract
The Palomar Transient Factory is an automated wide-field survey facility dedicated to identifying a wide range of
transient phenomena. Typically, a new 7.5 square degree field will be acquired every 90 seconds with 66% observing
efficiency, in g' band when the sky is dark, or in R band when the moon is up. An imaging camera with a 12Kx8K
mosaic of MIT/LL CCDs, acquired from CFHT, is being repackaged to fit in the prime focus mounting hub of the
Palomar 48-inch Oschin Schmidt Telescope. We discuss how we have addressed the broad range of issues presented by
this application: faster CCD readout to improve observing efficiency, a new cooling system to fit within the constrained
space, a low impact shutter to maintain reliability at the fast observing cadence, a new filter exchange mechanism, and
the field flattener needed to correct for focal plane curvature. The most critical issue was the tight focal plane alignment
and co-planarity requirements created by the fast beam and coarse plate scale. We built an optical profilometer system to
measure CCDs heights and tilts with 1 μm RMS accuracy.
HIPO data products
Show abstract
HIPO is a special purpose instrument for SOFIA, the Stratospheric Observatory For Infrared Astronomy. It is a high-speed,
imaging photometer that will be used for a variety of time-resolved precise photometry observations, including
stellar occultations by solar system objects and transits by extrasolar planets. HIPO will also be used during the test
program for the SOFIA telescope, a process that began with a series of ground-based tests in 2004. The HIPO
requirements, optical design, overall description, and an early look at performance and planned data acquisition modes
have appeared in earlier papers (e.g. Dunham, et al., Proc. SPIE 5492, 592-603 (2004)). This paper provides an update
to the instrument description, final lab measurements of instrument performance, and a discussion of the data produced
by the various observing modes.
Compact multi-band visible camera for 1m-class fast telescopes
Show abstract
Most of the small 1m-class telescopes designed for fast tracking of transient object, like GRBs, are equipped with
infrared and visible cameras, fed through a dichroic. We studied a new concept for a fast and compact multi-band visible
camera, using successive dichroics, to cover simultaneously many visible bands (U,B,V,R, and I), sampled with one
more CCD detectors. This extended spectral coverage will help to observe transient faint objects. To keep envelope size,
weight and overall cost at a reasonable level, a trade-off has been carried out.
SNDICE: a direct illumination calibration experiment at CFHT
Show abstract
We present the first results of the SuperNova Direct Illumination Calibration Experiment (SNDICE), installed
in January 2008 at the Canada France Hawaii Telescope. SNDICE is designed for the absolute calibration of
the instrumental response of a telescope in general, and for the control of systematic errors in the SuperNova
Legacy Survey (SNLS) on Megacam in particular. Since photometric calibration will a critical ingredient for
the cosmological results of future experiments involving instruments with large focal planes (like SNAP, LSST
and DUNE), SNDICE functions also as a real-size demonstrator for such a system of instrumental calibration.
SNDICE includes a calibrated source of 24 LEDs, chosen for their stability, spectral coverage, and their power,
sufficient for a flux of at least 100 electron/s/pixel on the camera. It includes also Cooled Large Area Photodiode
modules (CLAPs), which give a redundant measurement of the flux near the camera focal plane. Before installing
SNDICE on CFHT, we completed a full calibration of both subsystems, including a spectral relative calibration
and a 3D mapping of the beam emitted by each LED. At CFHT, SNDICE can be operated both to obtain a
complete one-shot absolute calibration of telescope transmission in all wavelengths for all filters with several
incident angles, and to monitor variations on different time scales.
An atmospheric corrector to work with FastCam at William Herschel Telescope
Show abstract
In this contribution an Atmospheric Dispersion Corrector (ADC) developed for the FastCam project is presented.
FastCam is a system based on 'lucky imaging' techniques for high spatial resolution, developed at the Instituto de
Astrofisica de Canarias (IAC). The use of a system to correct the atmosphere's effects is necessary to obtain a good
optics quality in order to satisfy science requirements.
Two alternatives for an atmospheric dispersion corrector for the instrument FastCam have been studied. One ADC has
been designed to be implemented and intended to correct that atmospherical effect at the 4.2m William Herschel
Telescope (Roque de los Muchachos Observatory, La Palma) for zenithal distances larger than 15 degrees, mainly in I
band. The excellent resolution reached with FastCam makes this effect to distort the images. This work presents the
design of an ADC as a pre-focus system of two prisms with variable separation in order to compensate the dispersion
until zenithal distances of 50°. Both are placed in a rotator to align the orientation of zenithal distorsion. The results for
this ADC has been tested in lab, and in May 2008, at the WHT; our next step will be to use it at the 10.4m Gran
Telescopio Canarias (GTC). Although the system is still under the final stages of its development, we want to implement
it to the new instruments for high spatial resolution.
The Keck-I Cassegrain ADC
Show abstract
We briefly describe the design, construction and performance of the recently-commissioned Atmospheric Dispersion
Corrector (ADC) for the Keck-I Cassegrain focus. This is a "longitudinal" ADC with fused silica prisms slightly over 1-
meter in diameter, designed to operate at zenith distances up to 60 degrees and over a 20 arcminute field-of-view with
negligible impact on image quality and throughput. It provides dispersion compensation from 0.31 to 1.1 microns. The
sol-gel-based antireflection coatings were a major technological challenge, and we encountered some previously
unrecognized performance consequences of the LADC design which should be considered before adopting this design.
The MagE spectrograph
Show abstract
The Magellan Echellette (MagE) spectrograph is a single-object optical echellette spectrograph for the
Magellan Clay telescope. MagE has been designed to have high throughput in the blue; the peak
throughput is 22% at 5600 Å including the telescope. The wavelength coverage includes the entire
optical window (3100 Å - 1 μm). The spectral resolution for a 1" slit is R~4100. MagE is a very
simple spectrograph with only four moving parts, prism cross-dispersion, and a vacuum Schmidt
camera. The instrument saw first light in November 2007 and is now routinely taking science
observations.
3D-NTT: a versatile integral field spectro-imager for the NTT
Show abstract
The 3D-NTT is a visible integral field spectro-imager offering two modes. A low resolution mode (R ~ 300 to 6 000)
with a large field of view Tunable Filter (17'x17') and a high resolution mode (R ~ 10 000 to 40 000)
with a scanning Fabry-Perot (7'x7'). It will be operated as a visitor instrument on the NTT from 2009.
Two large programmes will be led: "Characterizing the interstellar medium of nearby galaxies with 2D maps of
extinction and abundances" (PI M. Marcelin) and "Gas accretion and radiative feedback in the early universe" (PI J.
Bland Hawthorn). Both will be mainly based on the Tunable Filter mode. This instrument is being built as a
collaborative effort between LAM (Marseille), GEPI (Paris) and LAE (Montreal). The website adress of the instrument
is : http://www.astro.umontreal.ca/3DNTT
Posters: Instrumentation Techniques and Technologies
Commissioning of an integral-field spectro-polarimeter for PMAS
Show abstract
During 2007, a new polarimetric observing mode was added to the existing integral-field spectrograph PMAS. Initially,
this instrumental upgrade is aimed to measure the linear polarization states and to determine the three Stokes parameters
I, Q and U. The PMAS instrument offers an integral-field of view of up to 256 square arcseconds, while the spectrograph
covers a wavelength region from 340 to 900 nm. The paper presents the opto-mechanical design of the polarimetric unit,
summarizes calibration and test results and describes the first data taken during commissioning at the Calar Alto
observatory. Given the range of applications and the large parameter space (two spatial coordinates, one wavelength
dimension, plus polarimetric information), the realization of the PMAS 2D-Spectro-Polarimeter provides a unique
capability for night-time astrophysical observations, such as the study of scattering processes or magnetic fields for a
range of astronomical targets.
Comparison of precipitable water vapour measurements made with an optical echelle spectrograph and an infrared radiometer at Las Campanas Observatory
Show abstract
We present simultaneous precipitable water vapour (PWV) measurements made at the Las Campanas Observatory
in late 2007 using an Infrared Radiometer for Millimetre Astronomy (IRMA) and the Magellan Inamori
Kyocera Echelle (MIKE) optical spectrograph. Opacity due to water vapour is the primary concern for ground
based infrared astronomy. IRMA has been developed to measure the emission of rotational transitions of water
vapour across a narrow spectral region centred around 20 μm, using a 0.1 m off-axis parabolic mirror and a
sophisticated atmospheric model to retrieve PWV. In contrast, the MIKE instrument is used in conjunction
with the 6.5 m Magellan Clay telescope, and determines the PWV through absorption measurements of water
vapour lines in the spectra of telluric standard stars. With its high spectral resolution, MIKE is able to measure
absorption from optically thin water vapour lines and can derive PWV values using a simple, single layer
atmospheric model. In an attempt to improve the MIKE derived PWV measurements, we explore the potential
of fitting a series of MIKE water vapour line measurements, having different opacities.
Calibration issues for MUSE
Show abstract
The Multi-Unit Spectroscopic Explorer (MUSE) is an integral-field spectrograph for the VLT for the next decade. Using
an innovative field-splitting and slicing design, combined with an assembly of 24 spectrographs, MUSE will provide
some 90,000 spectra in one exposure, which cover a simultaneous spectral range from 465 to 930nm. The design and
manufacture of the Calibration Unit, the alignment tests of the Spectrograph and Detector sub-systems, and the
development of the Data Reduction Software for MUSE are work-packages under the responsibility of the AIP, who is a
partner in a European-wide consortium of 6 institutes and ESO, that is led by the Centre de Recherche Astronomique de
Lyon. MUSE will be operated and therefore has to be calibrated in a variety of modes, which include seeing-limited and
AO-assisted operations, providing a wide and narrow-field-of-view. MUSE aims to obtain unprecedented ultra-deep 3D-spectroscopic
exposures, involving integration times of the order of 80 hours at the VLT. To achieve the corresponding
science goals, instrumental stability, accurate calibration and adequate data reduction tools are needed. The paper
describes the status at PDR of the AIP related work-packages, in particular with respect to the spatial, spectral, image
quality, and geometrical calibration and related data reduction aspects.
MUSE: feeding and mounting 24 spectrographs
Show abstract
The Multi Unit Spectroscopic Explorer MUSE is an integral field device containing 24 spectrographs at the Nasmyth
focus of the VLT unit telescope. The total field size of 1'x1' needs to be split and separated into 24 sub-fields which are
relayed along a central structure into the entrance aperture of the individual spectrographs. The realization of the optics
for field splitting and separation as well as the relay optics to direct the light of the individual fields to the spectrographs
is described here. A very tight link exists between the relay optics system layout and the mechanical arrangement of the
spectrographs in the common central structure. A compact mounting is essential due to the restricted space for such a
large instrument even on the VLT Nasmyth platform. A suitable arrangement of vertical and horizontal stacking of the
spectrographs was found enabling their feeding from the unobstructed front side of the instrumental structure. The
central instrument mount was designed as a stiff structure absorbing print-through effects due to thermal mismatch with
the telescope platform but rigid enough to withstand earthquakes.
The GlobalJetWatch spectrographs: a fibre-fed spectrograph for small telescopes
Show abstract
The GlobalJetWatch project (www.globaljetwatch.net) will place small (0.5-metre) commerical telescopes
in four schools around the world. Each telescope will be equipped with a custom designed spectrograph,
currently being built by the Astrophysics sub-department of the University of Oxford. The scientific goal
of the project is to provide continual monitoring of a rosetta stone object, the micro-quasar SS433. In addition,
the project has a significant out-reach element, aiming to involve school children on four-continents
in front-line astronomical research. The spectrograph is a fibre-fed fixed format cross-dispersed echellete
design providing R~6000 spectra from 4300-8500 in a single exposure. The spectrograph is built almost
entirely from off-the-shelf components. The four GlobalJetWatch sites (Australia, India, South Africa,
Chile) will be commissioned in 2008/09. Here we present the baseline design of the spectrograph, and
initial results from the prototype on-sky commissioning in Oxford.
Optical design of the VLT Coudé path for visible-range instrumentation
Show abstract
This paper describes a proposed optical design for the ESO-VLT Coude path in the visible spectral range (380 to 800 nm). The optical train will be implemented in the four VLT Telescope Units in Paranal Observatory with the aim to feed simultaneously a high
resolution - high stable spectrograph in the Combined Coude Laboratory. Cost - performances
trade-offs are discussed as well.
The PAU camera
Show abstract
The Physics of the Accelerating Universe (PAU) is a new project whose main goal is to measure the baryon
acoustic oscillations (BAO) in the galaxy distribution to characterize dark energy. For this purpose, it will build
a new large field of view camera (the PAU Camera) to carry out a wide area imaging survey with narrow band
filters spanning the optical wavelength range. The PAU Camera is at an early stage of design. Currently, it is
designed to have a focal plane field of view of approximately 45cm in diameter, that will be densely populated
by state of the art CCDs. The PAU Camera will use a new set of approximately 45 narrow band filters ranging
from ~4200 to ~8700 angstroms with two additional wide band filters at the blue and red ends of the spectrum.
The camera will operate in drift-scan mode. The PAU Camera is expected to be mounted either in a purposely
designed 2.5m class wide field telescope or in an existing telescope that could be adapted to deliver a wide field.
HERMES: a high-resolution fiber-fed spectrograph for the Mercator Telescope
Show abstract
HERMES, a fiber-fed , high-resolution echelle spectrograph is currently in its integration phase at the 1.2-meter Mercator Telescope at the Roque de Los Muchachos Observatory on La Palma (Spain). The design of HERMES, optimized for high efficiency and high instrumental stability, is based on a large R2.7 echelle grating. It is operating in quasi-Littrow white-pupil configuration, with a double-prism as cross-disperser. It records the complete spectrum from 377 to 900 nm on one 2048×4608 pixel CCD in a single exposure. HERMES offers 1) a high-resolution and high-efficiency observation mode through a 80-μm optical fiber (2.5 arcsec sky aperture) equipped with a two-slice image slicer, resulting in a spectral resolution of R=85000 and a peak-efficiency above 25%; and 2) a high-stability mode through a 60-μm fiber (2.15 arcsec sky aperture, R=55000) equipped with a double fiber scrambler for improved spectrograph illumination stability. This mode is intended for high-precision radial velocity measurements and it offers the possibility of recording simultaneously the spectrum of a wavelength calibration lamp interlaced with the science spectrum. This allows for precise tracking of instrumental drifts during integration. To increase instrumental stability further, the spectrograph will be housed in a temperature and pressure controlled chamber. This spectrograph mounted on a flexible-scheduling telescope has a wide astronomical scope, going from asteroseismology to binary star research and chemical studies of stars and circumstellar material. In this contribution we present the final design of HERMES and we report on the project status.
A new two channel high-speed photo-polarimeter (HIPPO) for the SAAO
Show abstract
We report on the completion of a new 2 channel, HIgh speed Photo-POlarimeter (HIPPO) for the 1.9m optical telescope of the South African Astronomical Observatory. The instrument makes use of rapidly counter-rotating (10Hz), super-achromatic half- and quarter-waveplates, a fixed Glan-Thompson beamsplitter and two photo-multiplier tubes that record the modulated O and E beams. Each modulated beam permits an independent measurement of the polarisation and therefore simultaneous 2 filter observations. All Stokes parameters are recorded every 0.1sec and photometry every 1 millisecond. Post-binning of data is possible in order to improve the signal. This is ideal for measuring e.g. the rapid variability of the optical polarisation from magnetic Cataclysmic Variable stars. First light was obtained in February 2008.
MMT-Pol: an adaptive optics optimized 1-5µm polarimeter
Show abstract
MMT-POL is an adaptive optics optimized, 1-5μm imaging polarimeter for use at the 6.5m MMT. By taking full
advantage of the adaptive optics secondary mirror of the MMT, this polarimeter will offer for the first time on 8m class
telescopes, diffraction limited polarimetry with very low instrumental polarization. This instrument will permit
observations as diverse as protoplanetary discs, comets, red giant winds, galaxies and AGN. We discuss both the novel
instrument design and key science drivers.
Structure of the spectrograph ESOPO
Show abstract
The structure of the spectrograph ESOPO is the stiff mount that will maintain fixed all optics elements, electronics and
mechanical subsystems. The ESOPO spectrograph is a project of the "Instituto de Astronomia de la Universidad
Nacional Autonoma de Mexico" (IAUNAM) to upgrade its 2.1m telescope as a competitive facility for the next decade.
The scientific purpose is to obtain a modern high efficient intermediate-low dispersion spectrograph optimized for the
3500 - 9000 Å spectral interval with a spectral resolution of 500 ≤ R ≤ 5000. It is to be used at the cassegrain f/7.5 focus
of the 2.1 m telescope for general astronomical purposes. This work presents the mechanical design process and the form
in which the structure was verified to comply with the ESOPO's top level image quality and stability requirements. The
latter was not a lineal process. The way we resolved it is to run FEAs on the complete system and with the instrument in
different operation positions during a normal cycle of observations. These results are validated through the error budget
of the ESOPO. The structure is currently under construction.
Slit-mask, acquisition, and guiding zone mechanisms of the ESOPO spectrograph
Show abstract
This work presents the specifications, requirements, design, finite element analysis and results of the assembled
subsystems: slit-mask, and the acquisition and guiding zone mechanisms of the ESOPO spectrograph. This spectrograph
is a project of the Institute of Astronomy, National University of Mexico.
Two campaigns to compare three turbulence profiling techniques at Las Campanas Observatory
Show abstract
In preparation to characterize the Giant Magellan Telescope site and guide the development of its adaptive
optics system, two campaigns to systematically compare the turbulence profiles obtained independently with
three different instruments were conducted at Las Campanas Observatory in September, 2007 and January 2008.
Slope detection and ranging (SLODAR) was used on the 2.5-m duPont telescope. SLODAR measures the C2n
profile as a function of altitude through observations of double stars. The separation of the observed double
star sets the maximum altitude and height resolution. Ground layer (altitudes < 1 km) and free atmosphere
turbulence profiles are compared with those obtained with a lunar scintillometer (LuSci) and a multi-aperture
scintillation sensor (MASS), respectively. In addition, the total atmospheric seeing was measured by both
SLODAR and a differential image motion monitor (DIMM).
On-board calibration monitor for tracking instrument sensitivity
Show abstract
The On-board Calibration Monitor (OCM) is being developed as an integral component of the ACCESS instrument
and as a pathfinder for other missions. It provides stable full-aperture illumination of the telescope for
tracking the instrument sensitivity as a function of time. The light source is composed of an ensemble of LED
pairs with central wavelengths that span the spectral range of the instrument and illuminate a diffuser that is
observed by the full optical path. Feedback stabilization of the light source intensity is achieved by photodiode
monitoring of each LED. This stable source will provide real time knowledge of the ACCESS sensitivity throughout
the 5-year duration of the program. The present status of the design and laboratory evaluation of the OCM
system will be presented.
FMOS: the Fibre Multi-Object Spectrograph: Part VII. Results of PIR engineering run
Show abstract
Fibre Multi-Object Spectrograph (FMOS) is the next common-use instrument of Subaru Telescope. FMOS consists of
three subsystems; the Prime focus unit for Infrared (PIR), the fibre positioning system/connector units, and the two
infrared spectrographs. The PIR was transferred to the Subaru Observatory in the spring of 2005 to check the optical
performance on the telescope. As a result of the test observation, we found that the adjustment of the optical axis
between PIR and the primary mirror was difficult with the initial design of the corrector alignment stage. Furthermore,
the optical axis of the telescope moved over a little owing to an earthquake in Hawaii Island in Oct. 2006. Therefore we
decided to modify mechanical structure of PIR, the corrector alignment stage as well as the cable wrapping system. This
modification was completed in the summer of 2007. In this proceeding, we report the mechanical structure of the new
PIR and the results of the engineering observations.
Design and construction of the fibre system for FMOS
Show abstract
A consortium of Japanese, Australian and UK groups has developed a fibre-fed near IR (J & H band) multi-object spectrographic facility (FMOS) for the Subaru telescope. In this second-generation instrument, a novel prime focus 400-fibre multi-object positioning system, ECHIDNA, is optically linked via twin cables to dual IR spectrographs. The spectrographs are located some distance away, on a dedicated platform two levels above Nasmyth. The Centre for Advanced Instrumentation at Durham University oversaw the design and construction of the optical fibre system linking ECHIDNA to the spectrographs. A modularised connector within the cable scheme and an integral back illumination unit additionally featured as part of the Durham work-package. At the time of writing (mid 2008) FMOS, including the fibre system, is installed and functional on-telescope, with commissioning currently underway. This paper provides an overview of the design and construction of the optical fibre system.
NEFER: a high resolution scanning Fabry-Perot spectrograph
Show abstract
The scanning Fabry-Perot spectrograph could give highly accurate, kinematical information of star forming regions (HH
objects, protoplanetary disks and large scale flows) and the dynamics of isolated and interacting galaxies (resonances,
galaxy pairs, compact groups). In this project we are developing a high spectral resolution scanning Fabry-Perot
interferometer for the GTC 10 m telescope and the OSIRIS instrument. The system will provide the following
characteristics: high spectral resolution data (R up to 20000) over a whole field of view of approximate 8 × 8 arcmin,
0.125 arcsec pixel size in two spectral ranges; 6300 to 7000 Å (galactic projects) and 8000 to 9500 Å (OTELO objects
kinematics). ICOS ET100 Fabry-Perot will be used and installed within the OSIRIS collimated beam in the filter wheel
hosting the tunable filters. Several acquisition software features have been defined like: synchronizing Fabry-Perot
scanning with image acquisition, data cube assembly; single frame or data cube files would be provided according to the
observer data reduction process. Fabry-Perot plates parallelism is extremely important to improve Finesse. Our team has
developed an algorithm to accomplish this task.
GHαFaS: Galaxy Hα Fabry-Perot system for the WHT
Show abstract
GHαFaS is a new Fabry-Perot system available at the William Herschel Telescope. It was mounted, for the first
time, at the Nasmyth focus of the 4.2 m WHT in La Palma in 2007 July. With a spectral resolution of the order
R~15000 and a seeing limited spatial resolution, GHαFaS provides a new look at the Hα-emitting gas over a 4
arcminutes circular field in the nearby universe. Many types of objects can be observed with a scanning Fabry-Perot system on a 4.2 m class telescope such as galaxies, HII regions, planetary nebulae, supernova remnants
outflows from stars and the diffuse interstellar medium. Astronomers from the Laboratoire d'Astrophysique
Experimentale (LAE) in Montreal, the Laboratoire d'Astrophysique de Marseille (LAM), and the Instituto de
Astrofisica de Canarias (IAC), have inaugurated GHαFaS by studying in detail the dynamics of nearby spiral
galaxies. A robust set of tools for reducing and analyzing the data cubes obtained with GHαFaS has also been
developed.
Stabilized-speckle integral field spectroscopy: SPIFS
Show abstract
We describe an instrument concept and basic feasibility study for a new observational technique which we call
Stabilized-sPeckle Integral Field Spectroscopy (SPIFS). SPIFS will enable, under certain observational conditions and
constraints, low-to-modest-Strehl diffraction-limited imaging spectroscopy from large ground-based telescopes in the
optical bandpass (i.e. V, R, and I bands). SPIFS is capable of exploring important scientific niches which are not
currently available using existing high angular resolution techniques such as adaptive optics or speckle imaging, using
existing, relatively-inexpensive technology. Based on our simulations presented in a companion paper (Keremedjiev,
Eikenberry & Carson, 2008), SPIFS can provide integral field spectroscopy at ~15-mas resolution and ~3% Strehl over
the I-band with sky coverage of ~20% to 100% in the Galactic Plane and ~5% at the Galactic poles. We present an
overview of the SPIFS technique and simulated performance in realistic observations of the microquasar SS 433 to
demonstrate one simple example of the power of SPIFS.
SPIFS performance simulations: achieving diffraction-limited spatial resolutions for spectroscopy
Show abstract
We present the results of performance simulations characterizing the Stabilized sPeckle Integral Field Spectrograph (SPIFS). Our simulations of images distorted by Kolmogorov atmospheric turbulence confirm that stabilization of the single brightest speckle via a fast steering mirror (FSM) produces near-diffraction-limited spatial resolution for the red part of the visible spectrum (0.6 μm-1.0 μm). On a 10-meter class telescope this corresponds to an angle of ~13 mas. We also demonstrate that the Strehl ratio of the stabilized speckle will be between 1 and 3% for r0 = 20cm on a 10-meter class telescopes. The guide star limiting magnitude, through the use of a shutter, will be I=16.5. Simulations also reveal that the guide star can be as far away as 20" from the source and still recover tip-tilt information to drive SPIFS.
Visitor instruments in the ESO Very Large Telescope Observatory in Paranal
Show abstract
This paper is presenting the implementation of the concept of a Visitor Instrument at the Very Large Telescope
observatory of ESO at Paranal. The focus on the Nasmyth A of Melipal UT#3 (8m telescope) is dedicated to receive
these Visitor Instruments. This concept consists in the installation of an Instrument at the Visitor focus for an observation
run for a limited period of time, and then to remove the instrument. The selection of the instrument is done according to
its scientific and innovative outcome compared to the other ESO instruments already existing in the observatory. Once
granted an observation run of several nights, the visitor Instrument has to show its compliance with the requirements of
Paranal Observatory. Then the implementation and integration of the Visitor Instrument are scheduled according to the
needs of the Institute who developed the instrument. The instrument is installed at Paranal with the support of ESO staff.
The Visitor Instrument can be operated in 2 different modes according to its level of compliance to the ESO
specifications. Immediately after the observation run is finished, the instrument is removed from the Visitor Focus.
New read-out electronics concept for visual and infrared detector arrays in astronomical instrumentation
Show abstract
With the building of scientific camera systems for astronomical purposes in mind, the Max-Planck-Institut fuer
Astronomie (MPIA) has recently started developing new visual and infrared detector Read-out systems.
Due to the modular design, the electronics components can be configured for a wide range of currently available IR-detectors
and CCDs. The new Read-out Electronics are able to handle single or multiple detector systems with up to 144
input channels, feature high-speed data transfer and low power dissipation and additionally the system size is small and
lightweight.
The design is divided in four functional groups: controller board with variable Pattern Generator and fast fiber link,
clock/bias board, analog to digital converter board and the PCI data receiver board which writes the incoming data into
the computer memory. This design is highly versatile and allows for a wide variety of applications.
The high data transfer rate, small size and low heat dissipation makes these Read-out Electronics ideal for relatively
large focal plane arrays. The first instrument running with the new Read-out Electronics will be PANIC (Panoramic Near
Infrared Camera) at the 2.20 m telescope on Calar Alto.
Results of X-shooter data reduction software on laboratory frames
Show abstract
We present the current state of the Data Reduction Software (DRS) being developed at APC, Paris Observatory,
Amsterdam University and ESO for the X-shooter echelle spectrograph. X-shooter is the first VLT second
generation instrument, which will have its first light during the fall of the current year and will be available to
the astronomical community starting April 2009. The DRS will be fully integrated in the ESO VLT data flow
environment and it will use the ESO Common Pipeline Library. X-shooter data have two main characteristics,
on the one hand the exceptionally wide band (0.3 - 2.4 micron) covered in a single exposure, and on the other
hand the spectral format with highly curved orders and tilted lines. After a brief description of the reduction
process, the main results obtained up to now on simulated and laboratory data are reported. In particular the
precision of wavelength calibration and sky subtraction are discussed.
Wavelength calibration sources for instruments on extremely large telescopes
Show abstract
Extremely large telescopes (ELTs) and most of their instruments will be optimized for operating in the near
infrared (IR) because of the wavelength dependent performance of adaptive optics. Few established sources for
wavelength calibration exist in this wavelength domain. This project aims to provide the basic data to select
the best calibration sources for instruments at the European ELT (E-ELT) as a function of wavelength range
and spectral resolution. We have made use of the existing databases such as the NIST Atomic Spectra Database
as well as first principle physics and practical considerations to select about 20 hollow cathode lamps for study.
We are investigating their spectral and operational properties through laboratory measurements using a Fourier
Transform spectrometer at the European Southern Observatory (ESO). The most interesting sources will then be
studied at atomic physics laboratories, such as the US National Institute of Standards and Technology (NIST), in
order to produce accurate wavelength standards and calibration reference data directly applicable to operations
of E-ELT instruments. The resulting data archive will be used to recommend the best suited sources for the
instruments proposed for the E-ELT.
Selection of wavelength calibration features for automatic format recovery in astronomical spectrographs
Show abstract
Automated wavelength calibration requires line lists that are free of blended or unstable features at the resolution
of the spectrograph in order to avoid false matches. We present a procedure that will identify isolated features
suitable for use as wavelength standards. The procedure takes into account the expected signal to noise level
and the degree of uncertainty in the spectral format that defines how isolated the spectral features must be. Our
goal is to produce a customised list of features that can be unambiguously matched to observed features.
Investigation of residual blaze functions in slit-based echelle spectrograph
Show abstract
We have studied the Residual Blaze Functions (RBF) resulting from division of individual echelle orders by
extracted flat-field in spectra obtained by slit-fed OES spectrograph of 2m telescope of Ondrejov observatory,
Czech Republic. We have eliminated the dependence on target and observation conditions by semiautomatic
fitting of global response function, thus getting the instrument-only dependent part, which may be easily incorporated
into data reduction pipeline. The improvement of reliability of estimation of continuum on spectra of
targets with wide and shallow lines is noticeable and the merging of all orders into the one long spectrum gives
much more reliable results.
ACCESS: absolute color calibration experiment for standard stars
Show abstract
ACCESS is a recently approved rocket-borne payload with a ground-based calibration and performance monitoring
program that is designed to transfer the National Institute of Standards and Technology (NIST) absolute
laboratory standards to the stars with a precision and calibration accuracy of 1% across the 0.35-1.7μm bandpass.
This represents a significant improvement in the absolute and relative astrophysical flux calibration system,
particularly at near-infrared (NIR) wavelengths.
Establishing improved spectrophotometric standards is important for a broad range of missions and is relevant
to many astrophysical problems. In particular, the precise calibration of the flux scale across the bandpass
extending from 0.35-1.7 μm is fundamental to the precise determination of dark energy measurements based
on SNeIa photometry.
A high-resolution spectrograph for the solar telescope GREGOR
Show abstract
This communication shows the design, layout, mounting and start-up of a high-resolution grating spectrograph for VIS-NIR
at GREGOR 1.5m Solar Telescope (Observatorio del Teide, Tenerife, Canary Islands). The instrument will be used
together with the Tenerife Infrared Polarimeter (TIP-II). As special characteristics of the design, the following can be
mentioned: The first folding mirror of the spectrograph can be placed in two positions to take into account the change of the
optical axis introduced by the polarizing beamsplitter of TIP-II. This way the instrument is optimally aligned when used
in situations with and without polarimeter. The second and third mirrors rotate the image of the entrance slit, making it parallel to the grating grooves. A system of prisms are used to adequately fit onto the detector the two orthogonal polarized beams generated by the
polarimeter. Two output beams are possible, to make feasible simultaneous visible and near-infrared observations.
An intelligent modulator system
Show abstract
In 2001, the GONG+ instruments began acquiring solar magnetic field images (magnetograms) every minute.
These observations offer a useful resource for the solar physics community. However, the quality of the magnetograms
was reduced by a significant zero point error in the observations that varied across the solar image and with time. This
precluded using the magnetograms for meaningful extrapolations of weak photospheric fields into the corona. The error
was caused by the slow, asymmetric, locally varying switching of the LCD modulator (LCM) from one retardation state
to the other. This generated a false magnetic field pattern as a result of different responses to weak instrumental linear
polarization ahead of the LCM. The original modulator driver used a very simple design to excite the LCM. Liquid
crystals like those in the LCM take different times to switch from one polarization state to the other than to return to the
first polarization state. To eliminate the difference in switching times, a driver capable of varying its output during the
change in LCM state was needed. A microcontroller-based design was chosen. The final driver design resulted in a
factor of 100 improvement in the zero point error.
An EAGLE with arms: a solution to the design of the adaptive multi-IFU spectrograph EAGLE for the E-ELT
Show abstract
EAGLE is an adaptive multi-IFU spectrograph for the 42-m E-ELT. We present our design of the EAGLE Target
Acquisition System (TAS) and IFU system while the spectrograph design is part of a different paper. A modified design
of the arms of KMOS, a future multi-IFU spectrograph for the VLT, is used. Their shorter length permits to place more
arms in EAGLE than in KMOS. An unusual difficulty in designing the optics was the need for a very high image quality
in the pupil images on the deformable mirrors. The solution includes a lens in the arm more complex than in KMOS and
a series of mirrors after the arm. The IFU is an Advanced Image Slicer (AIS) with an unusually large anamorphic
magnification factor of 3.2. The design makes all IFU fields parallel in the telescope field wherever their positions. Both
the anamorphic factor of the AIS and the position of its exit pupil were adjusted to help reduce the size and simplify the
design of the spectrograph. The preceding design being our basic design, a different approach that takes advantage of the
small field of the main science cases will also be discussed. In this new concept, field selectors permit to have a choice of
a large number of small fields or a small number of large fields or a combination of both. Combined with the proper
adaptive optics system, the throughput of EAGLE would increase by a factor of more than 2 while maintaining the same
cost.
Science requirements for EAGLE for the E-ELT
Show abstract
We present an overview of the EAGLE science case, which spans spatially resolved spectroscopy of targets from five
key science areas - ranging from studies of heavily obscured Galactic star clusters, right out to the first galaxies at the
highest redshifts. Here we summarise the requirements adopted for the study and also evaluate the availability of natural
guide stars in example fields, which will impact on the adaptive optics performance and architecture.
Initial opto-thermal modelling of the EAGLE instrument to maximise SNR performance and resulting design considerations
Show abstract
E-ELT will provide a unique opportunity to observe the early universe since its large collecting area will allow detecting
faint objects at high redshifts. Primordial galaxies are a key topic for cosmology and for understanding the behaviour of
the galaxies in the universe. To achieve these observations, future instruments for the E-ELT will have to provide high
sensitivity over a wide range of wavelengths from 1 μm up to 2.5 μm - the upper limit being imposed by the redshift
which shifts the OII and Hα lines.
For the EAGLE instrument mainly devoted to such observations, we have studied the opto-thermal behaviour of the
complete system (TAS - Target Acquisition System - and the spectrograph) to estimate the thermal emission of the
optical and the mechanical parts which become a major contributor to the background above 2.2 μm. The nominal
operating temperature is a key parameter we must define precisely to both reduce the thermal background and optimise
the cooling system in terms of cost and complexity. The results of the simulations show that the TAS and the
spectrograph contribute to the thermal background at a similar level and what the optimal temperature should be. We
then discuss how such an 'optimal design' might be implemented in practice.
Specifying an MOAO-fed integral field spectrograph for the E-ELT
Show abstract
We present an end-to-end simulator for 3D spectroscopy, which can be used to specify MOAO-fed integral field
spectrographs dedicated to ELTs. This simulator re-scales either local data or outputs of hydro-dynamical simulations to
model distant galaxies. We present simulations of 3D observations in the H-band, for a rotating disk and a major merger
at z=4, and a large range of stellar-mass. We use these simulations to explore the parameter space, focusing on the
impact of the telescope diameter, total integration time, spectral resolution, and IFU pixel scale. The size of the telescope
diameter has little influence on the spatial resolution of 3D observations but largely influences the achieved SNR. The
choice of the IFU pixel scale is driven by the optimal "scale-coupling", i.e., the relation between the spatial resolution of
3D observations and the physical size of the features for which one needs to recover the kinematics using this IFU, and
the SNR achieved with this spatial scale. To recover the dynamical state of distant emission line galaxies, one of the
main goal of such future instruments, one only needs to recover their large-scale motions, which in turn requires only
relatively coarse IFU pixel scales (50-75 mas) and moderate spectral resolution (R=5000).
High contrast imaging feasibility study for FRIDA
Show abstract
FRIDA will be an Infrared Imager and an Integral Field Spectrograph (IFS) for the 10.4m Gran Telescopio
Canarias (GTC). This instrument is scheduled to be installed in 2010, at the Nasmyth A platform of the GTC,
behind GTCAO (the Adaptive Optics [AO] system of the GTC). FRIDA design incorporates straightforward
upgrade paths for focal plane masks. In this work, we analyze the capability of FRIDA to provide high dynamic
range images. Different coronagraphic configurations could be inserted within FRIDA optical assembly.
We quantify numerically their performance in presence of AO compensated wavefronts. Thereafter, numerical
simulations about the Simultaneous Spectral Differential Imaging1 (SSDI) method are presented. This technique
aims to suppress the AO residual speckles and can be applied to selected frames of the data cube, provided by
FRIDA in IFS mode. Therefore, we estimate the starlight attenuation that could be reached with the association
"Coronagraph + SSDI method" for the ground-based instrument "GTC + GTCAO + FRIDA".
Multi-stage apodized pupil Lyot coronagraph experimental results
Show abstract
Prolate (Pupil) Apodized Lyot Coronagraphs (PPALC) are known to offer optimal performances for a Lyot-type
Coronagraph configuration, i.e. with an opaque occulting focal mask. One additional benefit of PPALC is its possible
use in a multi-stage configuration. In theory, the coronagraphic performance can be QN, where Q is the energy rejection
factor of one stage (the first one), and N the number of stages. Several ground-based telescopes are considering PPALC
as an option for their high-contrast instrumentation (e.g. Gemini/GPI, EELT/EPICS, Subaru HiCIAO). Although the
PPALC suffers from several limitations, several works are currently focused on fabricating entrance pupil apodizers and
trying to find ways to overcome chromatism issues. In this work, we present the first experimental results from Multi-Stage PPALC (MS-PPALC) that was done in the context of the Japanese space telescope SPICA coronagraph project.
Our entrance pupil apodizers use small diameter High Energy Beam Sensitive glass (HEBS-glass) from Canyon
Materials Inc. The current results show modest coronagraphic performance due to uncompensated phase aberrations
inherent to HEBS-glass material. In addition, and due to these uncompensated phase aberrations, the present optical
configuration is an altered version of the originally planned set-up. However, we can demonstrate the validity the MS-PPALC
concept and compare it to numerical simulations.
Novel dispersive elements for LIRIS
Show abstract
New dispersive elements providing relative high resolution (R=2200) have been recently incorporated in the near
infrared spectrograph LIRIS. These elements are founded on a rather novel design based on a diffractive pattern
engraved in fused silica, which is placed between two prisms. These new components are pushing forward the scientific
capabilities of the instrument by enhancing the medium resolution spectroscopic mode of operation. Details on the
design, specifications and measured performances, as well as aspects related to the integration and astronomical tests in
the instrument are presented.
High-efficiency silicon immersion grating by electron-beam lithography
Show abstract
Silicon immersion grating have opened the new possibilities of building compact high-resolution cryogenic spectrometers
for the near-infrared (NIR) region from 1.4 to 5.5μm. We are developing a silicon immersion grating
for a next-generation NIR high-resolution spectrometer attached to the Subaru 8.2 m telescope. Since a long
time, the anisotropic wet etching technique using photolithography has used for the fabrication of silicon immersion
gratings (e.g., Wiedemann & Jennings1 and Keller et al.2). Here, we present an alternative technique using
electron-beam (EB) lithography, which does not employ either any photolithography masks or UV light source.
This technique uses "direct" EBs to expose the resist. The EBs are precisely controlled by using a closed-looped
system comprising a laser interferometer. As compared to photolithographic technique, this technique results
in more accurate groove pitches and lower surface roughness near the edge of the mask. We fabricate a sample
grating with a groove pitch of 30 µm and a blaze angle of 69° on a 10mm × 20mm × 2mm flat substrate by
EB lithography. Our detailed optical testing of the grating using visible laser shows good optical performances:
extremely low scattered light (< 0.9%), less production of ghost light (< 0.01%), and high relative diffraction
efficiency (~ 88%). We plan to fabricate the final immersion grating by fixing the etched grating substrate to
a silicon prism using the optical-contact method. We are in the middle of R&D of this process and found that
much tighter optical-contact than usual seems to be required because of the high incidence angle to the contact
surface. Our first sample immersion grating shows a significant reflection loss at the contact surface when it is
used in an immersion mode with a NIR laser beam. We are trying to improve the polishing process of the thin
silicon substrate for better contact.
Silicon immersion grating spectrograph design for the NASA Infrared Telescope Facility
Show abstract
We present a conceptual design for an innovative infrared cross-dispersed spectrograph for the NASA Infrared
Telescope Facility (IRTF) at Mauna Kea. This facility-class instrument will provide a resolving power of up to 80,000 at
1.2-2.5 μm and 67,000 at 3-5 μm with a minimum slit width of 0.25". The instrument employs a silicon immersion
grating in order to reduce the size of the instrument. The design incorporates a 2048×2048 infrared array for the
spectrograph and an infrared slit viewer. The optical design is optimized for the thermal infrared (2.8-5.5 μm).
Cable tension real-time measure system based on RTLinux
Show abstract
To meet the need of feed control, Cable Tension Real-time Measure System based on RTLinux was established. And the
system is used to keep those cables healthy and safe. Resistance tension sensors are used in the system, and differential
holodesmosomes are also used in the system to raise system performance. Bad data checking in software raised the
performance of anti-interference.
Investigation of focal ratio degradation in optical fibres for astronomical instrumentation
Show abstract
A differential method was used to investigate the focal ratio degradation (FRD) exhibited by, and throughput of, a
selection of current-generation optical fibres. These fibres were tested to establish which would be best suited to feed
the High Resolution Spectrograph being built for the Southern African Large Telescope (SALT), as well as for future
instruments on WIYN and SALT. The double re-imaging system of Bershady et al. (2004) was substantially modified to
improve image quality and measurement efficiency, and to permit a direct FRD-measurement in the far-field. The re-imaging
method compares the beam profile produced by light which passes through a fibre to that which does not.
Broad and intermediate band-pass filters were used between 400-800 nm to test for wavelength dependence in the
observed FRD over a wide range in beam-speeds. Our results continue to be at odds with a mico-bend model for FRD.
We conclude that the new Polymicro FBP fibre is the most suitable product for broadband applications.
Optical design of FRIDA, the integral-field spectrograph and imager for the AO system of the Gran Telescopio Canarias
Show abstract
FRIDA (inFRared Imager and Dissector for the Adaptive optics system of the Gran Telescopio Canarias) has been
designed as a diffraction limited instrument that will offer broad and narrow band imaging and integral field
spectroscopy (IFS) capabilities with low, intermediate and high spectral resolutions to operate in the wavelength range
0.9 - 2.5 μm. The integral field unit is based on a monolithic image slicer based on the University of Florida FISICA.
Both, the imaging mode and IFS observing modes will use the same Rockwell 2K×2K detector. FRIDA will be based at
a Nasmyth focus of GTC, behind the GTCAO system. The FRIDA optical design, stray light analysis, tolerance analysis
and manufacturing feasibility are described in this contribution.
Experiment of Wide Field Cryogenic Telescope II (WFCT II) at Sutherland, South African Astronomical Observatory
Show abstract
We have developed Wide Field Cryogenic Telescope II (WFCT II) which contains a whole telescope-optics together with a detector in a vacuum case for cooling to suppress thermal emission from a telescope. The telescope inside is a Ritchey-Chretien system with an aperture of 220 mm and a focal length of 1540 mm. Light from celestial objects enters the telescope through a window, hits primary and secondary mirrors, passes through a filter, and reaches a detector. Spiders, baffles, and radiation shields are cooled down to ~80 K or lower by a refrigerator. All the optics reach a low temperature by exchanging heat with the radiation shields. A 1024×1024 InSb infrared array detector covers a field of view of 1 square degree with resolution of 3".5/pixel. The detector is also cooled by the refrigerator and is regulated at 29 ± 0.1 K. WFCT II is mounted on a small equatorial mounting whose size is 1 m in height, 1 m in width, and 1.2 m in length along the N-S direction. The main targets are diffuse emissions radiated from hydrogen atoms, molecules, and carbonaceous materials in star formation regions and the Galactic Center. We have started to obtain scientific data at Sutherland, South African Astronomical Observatory since December 2007.
Calibration and modeling support for instruments at ESO
Show abstract
We describe the activities of the Physical Modeling Group in ESO's Instrumentation Division related to the calibration
and physical description of an instrument with the objective to support the data reduction of science data and to facilitate
operations. We will use CRIRES and X-shooter as examples to describe the general concept. The core contribution of the
group consists of four parts: a) Optical model: describing the configurations of the optical elements of the spectrograph
based on engineering information; b) Calibration Reference Data: examples are: Wavelength standards traceable to
laboratory standards form the basis for the application of the 2-D wavelength calibration; spectro-photometric standard
stars to support flux calibration; physical properties of optical components such as the refractive index (Τ, λ) of a
disperser. c) support for Data Reduction Software (DRS) development: simulated data based on a model based
description of the instrument; d) general Project Support such as participation in Testing, Commissioning and Science
Verification. These tasks have been performed and documented in close collaboration with the project teams and the
software development groups. In summary, we have found that the use of instrument physical modeling techniques can
be beneficial during all phases of the life of an instrument: design, optimization, manufacture, testing and operations.
Once fully integrated in the project plan and scheduling direct and tangible benefits to the overall project result. Hence
planning for VLT 2nd generation and E-ELT instruments should make full use of these capabilities.
The COS calibration pipeline and verification process
Show abstract
The Cosmic Origins Spectrograph,1 COS, will be installed in the Hubble Space Telescope (HST) during the next
servicing mission. This will be the most sensitive ultraviolet spectrograph ever flown aboard the HST.
The calibration pipeline (CALCOS), written in Python, has been developed by the Space Telescope Science
Institute (STScI) to support the calibration of HST/COS data. As with other HST pipelines, CALCOS uses an
association table to specify the data files to be included, and employs header keywords to specify the calibration
steps to be performed and the reference files to be used.
CALCOS is designed with a common underlying structure for processing far ultraviolet (FUV) and near
ultraviolet (NUV) channels which, respectively, use a cross delay line and a Multi Anode Microchannel Array
(MAMA) detector. The pipeline basics and channel dependent specifics are presented. The generation and
application of the current reference files, derived from ground-based calibration data, is described, along with
the pipeline verification process and results.
The CALCOS calibration includes pulse-height filtering and geometric correction for the FUV channel; flat-field,
deadtime, and Doppler correction for both channels. Methods for obtaining an accurate wavelength calibra-tion
using the on-board spectral line lamp are described. The instrument sensitivity is applied to the background
corrected spectrum to produce the final flux calibrated spectrum.
The Southern African Large Telescope (SALT) calibration system
Show abstract
This paper presents details of the instrument calibration system employed on the SALT. It is designed to inject light into
the Spherical Aberration Corrector at about the position of the primary mirror caustic, thereby simulating the same
degree of vignetting as experienced by celestial objects. A light-shaping diffuser screen, coupled with Fresnel lenses,
modifies the beam to increase efficiency and attempt to illuminate the detectors in the same manner as a uniform sky.
Light is conveyed by means of liquid light guides from either QTH flat field lamps or a choice of hollow cathode
(CuAr, ThAr) and penray (Ar, Hg, Xe, Ne) lamps, used for wavelength calibration. Changing entrance pupil effects are
accounted for by employing a moving exit pupil baffle, which can simulate the pupil geometry of a specific track.
Snodar: a new instrument to measure the height of the boundary layer on the Antarctic plateau
Show abstract
The height of the atmospheric boundary layer on the Antarctic plateau is of particular importance to designers of optical
telescopes for Antarctica. Snodar was developed at the University of New South Wales to measure the height of the
atmospheric boundary layer at Dome A and Dome C on the Antarctic plateau. Snodar, or Surface layer Non-Doppler
Acoustic Radar, is a true monostatic high-frequency acoustic radar (SODAR) operating between 5 kHz and 15 kHz. As
the height of the boundary layer at Dome C is expected to be less then 30 m, and unknown at Dome A, Snodar was
designed to have a minimum sampling height of 5 m with a vertical resolution of 1 m or better. Snodar uses a PC/104
computer to perform signal processing in real time, and a USB sound card for low-latency analog IO. Snodar was
designed to run autonomously storing data on USB flash disks for retrieval the following summer, while uploading of
data acquisition scripts and spot checking of data is possible via Iridium satellite through UNSW's PLATO facility.
Snodar also incorporates a unique in-situ calibration sphere. We present details of the design and results from testing of
Snodar.
RISE: a fast-readout imager for exoplanet transit timing
Show abstract
By the precise timing of the low amplitude (0.005 - 0.02 magnitude) transits of exoplanets around their parent
star it should be possible to infer the presence of other planetary bodies in the system down to Earth-like
masses. We describe the design and construction of RISE, a fast-readout frame transfer camera for the Liverpool
Telescope designed to carry out this experiment. The results of our commissioning tests are described as well as
the data reduction procedure necessary. We present light curves of two objects, showing that the desired timing
and photometric accuracy can be obtained providing that autoguiding is used to keep the target on the same
detector pixel for the entire (typically 4 hour) observing run.
Hyper Suprime-Cam: back-end electronics for CCD readout
Show abstract
The development status of a prototype readout module for Hyper Suprime-Cam, a next-generation prime-focus camera
for the 8.2 m Subaru Telescope, is presented. The camera has a field of view 1.5° in diameter, and produces 2.1 Gbyte of
data per exposure. The module transfers the data to computers of a data acquisition system using TCP/IP and Gigabit
Ethernet. We have measured the performance of data processing and data transfer of the developed module. The results
indicated sufficient performance to read data from all CCDs within the required readout time.
CCCP: a CCD controller for counting photons
Show abstract
CCCP, a CCD Controller for Counting Photons, is presented. This new controller uses a totally new clocking architecture
and allows to drive the CCD in a novel way. Its design is optimized for the driving of EMCCDs at up to 20MHz of pixel
rate and fast vertical transfer. Using this controller, the dominant source of noise of EMCCDs at low flux level and high
frame rate, the Clock Induced Charges, were reduced to 0.001 - 0.0018 electron/pixel/frame (depending of the electron
multiplying gain), making efficient photon counting possible. CCCP will be deployed in 2009 on the ESO NTT through
the 3D-NTT1 project and on the SOAR through the BTFI project.
The University of Florida's next-generation cryogenic infrared focal plane array controller system
Show abstract
The Infrared Instrumentation Group at the University of Florida has substantial experience building IR focal plane array
(FPA) controllers and seamlessly integrating them into the instruments that it builds for 8-meter class observatories,
including writing device drivers for UNIX-based computer systems. We report on a design study to investigate
implementing an ASIC from Teledyne Imaging Systems (TIS) into our IR FPA controller while simultaneously
replacing TIS's interface card with one that eliminates the requirement for a Windows-OS computer within the
instrument's control system.
The Dark Energy Survey CCD imager design
Show abstract
The Dark Energy Survey is planning to use a 3 sq. deg. camera that houses a ~ 0.5m diameter focal plane of 62 2k×4k
CCDs. The camera vessel including the optical window cell, focal plate, focal plate mounts, cooling system and thermal
controls is described. As part of the development of the mechanical and cooling design, a full scale prototype camera
vessel has been constructed and is now being used for multi-CCD readout tests. Results from this prototype camera are
described.
Cooling the Dark Energy Camera instrument
Show abstract
DECam, camera for the Dark Energy Survey (DES), is undergoing general design and component testing.
For an overview see DePoy, et al in these proceedings. For a description of the imager, see Cease, et al in
these proceedings. The CCD instrument will be mounted at the prime focus of the CTIO Blanco 4m
telescope. The instrument temperature will be 173K with a heat load of 113W. In similar applications,
cooling CCD instruments at the prime focus has been accomplished by three general methods. Liquid
nitrogen reservoirs have been constructed to operate in any orientation, pulse tube cryocoolers have been used
when tilt angles are limited and Joule-Thompson or Stirling cryocoolers have been used with smaller heat
loads. Gifford-MacMahon cooling has been used at the Cassegrain but not at the prime focus. For DES, the
combined requirements of high heat load, temperature stability, low vibration, operation in any orientation,
liquid nitrogen cost and limited space available led to the design of a pumped, closed loop, circulating
nitrogen system. At zenith the instrument will be twelve meters above the pump/cryocooler station. This
cooling system expected to have a 10,000 hour maintenance interval. This paper will describe the
engineering basis including the thermal model, unbalanced forces, cooldown time, the single and two-phase
flow model.
Front-end electronics for the Dark Energy Camera (DECam)
Show abstract
The Dark Energy Survey Camera (DECam), when completed, is going to have one of the largest existing focal planes,
equipped with more than 70 CCDs. Due to the large number of CCDs and the tight space on the camera, the DECam
electronics group has developed new compact front-end electronics capable of flexibly and rapidly reading out all the
focal plane CCDs. The system is based on the existing MONSOON Image Acquisition System designed by the National
Optical Astronomy Observatory (NOAO), and it is currently being used for testing and characterization of CCDs. Boards
for the new readout are being developed in USA and Spain, with the first prototypes already produced and tested. The
next version with some improvements will be tested during 2008 and the system will be ready for production at the
beginning of 2009. Custom MONSOON boards and the electronics path will be described.
Bias selecting in TEXES electronics
Show abstract
TEXES is a high resolution mid-infrared spectrograph acting as a visiting instrument at the NASA IRTF and Gemini
North telescopes. Switching from high (R=100,000) to medium resolution (R=15,000), the noise becomes detector
dominated due to charge cascades in the low-background detector. This is remedied by lowering the bias voltage across
the detector, a problem during observing runs as it requires manual adjustment within the electronics. To save telescope
time, a bias selector has been created to allow the bias voltage to be switched from the control room between four
options. The options were chosen based upon signal to noise vs. bias voltage testing.
Daisy chain expandable readout system for infrared arrays
Show abstract
We have developed a control system for infrared array detectors with 16, 32 or more outputs. Our system consists of five boards (clock pattern generator, clock driver, A/D converter, parallel-in, and isolation), and is operated with a Linux (kernel 2.4 or 2.6) PC. It is capable of supplying 24 DC bias voltages and 16 clock voltages,
adjustable between -7.5V and +7.5V and the shortest clock width of 156 ns. One A/D board converts 16 analog array outputs to digital data simultaneously using 16 A/D converters. The rms of A/D conversions for fixed voltages is 2-3 ADU (or 150-200 μV) at a sampling rate of 250 kSPS. The parallel-in board has 32 optically
isolated input channels, and can receive data from 2 A/D boards simultaneously. The maximum data rate to
main memory of PC is 40 MB/sec, corresponding to 20 frames/sec of a 1024×1024 array. Our system is now
utilized for Aladdin 2 (InSb, 1024×1024, 32 outputs) of Wide Field Cryogenic Telescope 2 and SB-774 (Si:As, 320×240, 16 outputs) of 17μm Fabry-Perot spectrometer. The A/D boards have daisy-chain capability for next generation arrays with more than 32 outputs. In the daisy-chain mode, all A/D converters are triggered simultaneously, but the A/D boards make time-delayed data transfer. The parallel-in board receives data sequentially by every 32 A/D converters. When we apply our system for 2048×2048 detectors with 64 outputs, the frame rate will be 5 frames/sec.
Design and implementation of an improved chilled water glycol system for NICI array electronics thermal enclosure
Show abstract
The Near Infrared Chronographic Imager (NICI) being commissioned at Gemini was upgraded with a more powerful
Chilled Water Glycol System to address early overheating problems. The previous system was replaced with a
completely new design favoring improved airflow and increased heat transfer capabilities. The research leading to this
upgrade showed a significant lack of cooling power of the original design. The solution was a combination of
commercial heat exchanger and fans and a custom built enclosure.
As a prime infrared telescope facility, Gemini is very much interested in maintaining the least amount of heat dissipated
to the ambient air. The results obtained through the implementation of this solution will be helpful in understanding the
state of other existing electronics enclosures as well as those for new instruments to come. With the advent of electronic
intensive AO systems, future electronics enclosures must take full advantage of improved cooling. This paper describes
the design and implementation phases of the project. The results under maximum operating capacity proved to be within
the expected theoretical values and were deemed successful.
The Extreme Polarimeter (ExPo): design of a sensitive imaging polarimeter
Show abstract
The Extreme Polarimeter (ExPo) is approaching its first deployment at the 4.2 m William Herschel Telescope at La
Palma. This imaging polarimeter, developed at the Astronomical Institute of Utrecht University, aims to study
circumstellar material at a contrast ratio with the central star of 10-9. Working at visible wavelengths, it will provide an
inner working angle down to 0.5 arcsec and a field of view of 20 arcsec diameter. ExPo employs a dual beam-exchange
technique based on polarimeter designs for solar studies. A partially transmitting coronagraph mask placed in the first
focus reduces the light of the star. The beam is modulated using three ferro-electric liquid crystals in a Pancharatnam
configuration, then split in a polarizing beamsplitter. Both beams are re-imaged onto the same Electron-Multiplying
CCD camera.
We present the design of the ExPo instrument, highlighting the elements that are critical to the polarimetric performance.
Some prototype laboratory experiments demonstrating the instrument concept are discussed. These have been performed
using our realistic exoplanet laboratory simulator.
GFP-IFS: a coronagraphic integral field spectrograph for the APO 3.5-meter telescope
Show abstract
We present the design and initial laboratory tests of a new integral-field spectroscopy mode to be added to the Goddard
Fabry-Perot instrument at Apache Point Observatory. This new IFS mode incorporates a 'TIGER'-style lenslet array,
with pre-optics to allow spatial sampling of 0.21 or 0.42 arcseconds, corresponding to fields-of-view of 7 or 14
arcseconds. For coronography, we insert a mask close to the lenslet array focal plane, blocking a discrete number of the
lenslet foci. Three VPH grisms will be available to disperse the spectra, with medium-resolution (R~1000) red (λ ~
660nm) and green (λ ~ 490nm) modes and a high-resolution (R~5000) red mode. We show that it is possible to reduce
crosstalk between spectra by at least an order of magnitude by placing a pinhole mask at the focus of the lenslet array,
and present data on the throughput of the lenslets and VPH grism.
ACAM: a new imager/spectrograph for the William Herschel Telescope
Show abstract
ACAM will be mounted permanently at a folded-Cassegrain focus of the WHT. It can be used for broad-band
or narrow-band optical imaging of an 8.3-arcmin field, or for low-resolution (R ~ 500) spectroscopy. As the
only wide-field optical imager at the Cassegrain focus, ACAM is designed to cater for a broad range of science
programmes, including those requiring rapid response (e.g. gamma-ray bursts, supernovae) or scheduling at
awkward intervals (e.g. successive exoplanet transits), and those requiring the use of many filters (e.g. Hα
mapping of low-redshift galaxies). The imaging requirements alone are demanding, requiring a trade-off between
field of view (> 8 arcmin), PSF (<< seeing), wavelength coverage (UV to near-IR), throughput (> 0.8) and
radius-dependent wavelength shift (< 0.5 nm, for narrow-band filters). We discuss how the trade-off was effected
and present the final optical and mechanical design, and the expected performance.
Thermal gradient analysis for the ESOPO spectrograph
Show abstract
ESOPO will be a spectrograph of medium resolution for the 2.1 m telescope of the National Observatory at San
Pedro Martir, Baja California, Mexico. It has been developed by the Instituto de Astronomia of the Universidad
Nacional Autonoma de Mexico (IA-UNAM). The main goal of this instrument is to modernize the capabilities
of making science with that particular telescope. It is planned to achieve a spectral resolution between 500 and
5000. ESOPO is split into two arms; each one specialized in a specific wavelength range covering together all the
visible light. A very important issue in spectrographs is to avoid inside thermal gradients. Different temperatures
in the optical elements produce mechanical movements and image quality degradation during an exposition. The
error budget analysis developed for ESOPO allows establishing the required limits for temperature gradients. In
this paper is described the thermal analysis of the spectrograph, including specifications, finite element models,
thermal equations and expected thermal gradients.
Design, construction, and performance of VIRUS-P: the prototype of a highly replicated integral-field spectrograph for HET
Show abstract
We describe the design, construction, and performance of VIRUS-P (Visible Integral-field Replicable Unit
Spectrograph - Prototype), the prototype for 150+ identical fiber-fed integral field spectrographs for the Hobby-Eberly
Telescope Dark Energy Experiment (HETDEX). VIRUS-P was commissioned in 2007, is in regular service on the
McDonald Observatory 2.7 m Smith telescope, and offers the largest field of any integral field spectrograph. The 246-fiber IFU uses a densepak-type fiber bundle with a 1/3 fill factor. It is fed at f/3.65 through a telecentric, two-group
dioptric focal reducer. The spectrograph's double-Schmidt optical design uses a volume phase holographic grating at
the pupil between the articulating f/3.32 folded collimator and the f/1.33 cryogenic prime focus camera. High on-sky
throughput is achieved with this catadioptric system by the use of high reflectivity dielectric coatings, which set the
340-670 nm bandwidth. VIRUS-P is gimbal-mounted on the telescope to allow short fibers for high UV throughput,
while maintaining high mechanical stability. The instrument software and the 18 square arcmin field, fixed-offset guider
provide rapid acquisition, guiding, and precision dithering to fill in the IFU field. Custom software yields Poisson noise
limited, sky subtracted spectra. The design characteristics are described that achieved uniformly high image quality with
low scattered light and fiber-to-fiber cross talk. System throughput exceeds requirements and peaks at 40%. The
observing procedures are described, and example observations are given.
Volume phase holographic grating performance on the VIRUS-P instrument
Show abstract
The Visible Integral-field Replicable Unit Spectrograph Prototype (VIRUS-P) has been in operation on the
Harlan J Smith 2.7m Telescope at McDonald Observatory since October of 2006. The prototype was created to
test the design and science capabilities of the full VIRUS instrument, wherein 150 copies of the spectrograph will
be installed on the Hobby Eberly Telescope (HET). We here discuss the specialized test bench built to assess
the blue optimized Volume Phase Holographic (VPH) grating performance. We also give lab and on-telescope
efficiency measurements for three such gratings in the wavelength range 3400-6800Å. Two sources of stray light
relevant to most spectrograph designs are also discussed.
Mechanical design of VIRUS-P for the McDonald 2.7m Harlan J. Smith Telescope
Show abstract
We present the mechanical and opto-mechanical design for the Prototype Visible Integral-Field Unit Spectrograph
(VIRUS-P). The VIRUS-P instrument is the single unit prototype for the planned VIRUS instrument which consists of
192 spectrographs for the Hobby Eberly Telescope Dark Energy Experiment (HETDEX). The VIRUS Prototype is a test
bed for the design and will be used for a survey on the McDonald 2.7m Harlan J. Smith Telescope. The mechanical
design is driven by the need for high stability. The structure of the instrument is aluminum but the internal optical
elements of the collimator and the camera are held in alignment with respect to each other using Invar metering rods.
The spectrograph is fiber fed with 246 fibers in a hexagonal packing pattern at the telescope focal plane Integral Field
Unit (IFU) and arranged in a slit at the input to the spectrograph. The reverse-Schmidt collimator articulates, and the
Volume Phase Holographic (VPH) grating rotates independently relative to the fixed Schmidt camera to allow for
versatile grating configurations during the prototype testing. Since the VIRUS spectrograph units will be mounted in a
gravity neutral configuration on the HET, the prototype instrument is mounted on a gimbal at the folded cassegrain port
of the 2.7m Smith Telescope to negate gravity vector changes.
VIRUS-W: an integral field unit spectrograph dedicated to the study of spiral galaxy bulges
Show abstract
We present the design, layout and performance estimates for a fiber based Integral Field Unit spectrograph.
This instrument is built for flexible use at different telescopes, and in particular for the new 2m telescope on
Mount Wendelstein in the Bavarian Alps. Based on the VIRUS spectrograph for the HETDEX experiment,
the proposed instrument will have a fiber head consisting of 267 optical fibers. The large angular field of
view of 150×75 arcseconds will allow full coverage of the bulge regions of most local late type galaxies in one
or two pointings. Realized by the usage of VPH gratings, a R ≈ 2500 and a R ≈ 6800 mode with 850Å and
515Å wavelength coverage will be dedicated to the study of stellar populations and kinematics of late type
galaxy bulges.
Extreme multiplex spectroscopy at wide-field 4-m telescopes
Show abstract
We describe the design and science case for a spectrograph for the prime focus of classical 4-m wide-field telescopes
that can deliver at least 4000 MOS slits over a 1° field. This extreme multiplex capability means that 25000 galaxy
redshifts can be measured in a single night, opening up the possibilities for large galaxy redshift surveys out to z~0.7 and
beyond for the purpose of measuring the Baryon Acoustic Oscillation (BAO) scale and for many other science goals.
The design features four cloned spectrographs and exploits the exclusive possibility of tiling the focal plane of wide-field
4-m telescopes with CCDs for multi-object spectroscopic purposes. In ~200 night projects, such spectrographs have the
potential to make galaxy redshift surveys of ~6×106 galaxies over a wide redshift range and thus may provide a low-cost
alternative to other survey routes such as WFMOS and SKA. Two of these extreme multiplex spectrographs are currently
being designed for the AAT (NG1dF) and Calar Alto (XMS) 4-m class telescopes. NG2dF, a larger version for the AAT
2° field, would have 12 clones and at least 12000 slits. The clones use a transparent design including a grism in which all
optics are smaller than the clone square subfield so that the clones can be tightly packed with little gaps between the
contiguous fields. Only low cost glasses are used; the variations in chromatic aberrations between bands are
compensated by changing one or two of the lenses adjacent to the grism. The total weight and length is smaller with a
few clones than a unique spectrograph which makes it feasible to place the spectrograph at the prime focus.
Optical-mechanical operation of the F2T2 filter: a tunable filter designed to search for First Light
Show abstract
The Flamingos-2 Tandem Tunable filter is a tunable, narrow-band filter, consisting of two Fabry-Perot etalons in series,
capable of scanning to any wavelength from 0.95 to 1.35 microns with a spectral resolution of R~800. It is an accessory
mode instrument for the near-IR Flamingos-2 imaging-spectrograph designed for the Gemini South 8m Observatory and
will be fed through the upcoming Multi-Conjugate Adaptive Optics feed. The primary science goal of the F2T2 filter is
to perform a ground-based search for the first star forming regions in the universe at redshifts of 7 < z < 11. The
construction of the F2T2 filter is complete and it is currently in its calibration and commissioning phases. In this
proceeding, we describe the calibration and performance of the instrument.
The Smart Tunable Filter for ELT
Show abstract
The Smart Tunable Filter is a new spectrograph providing a continuous field of view of 4'×4' sampled at 56 mas using
the technology of imaging Bragg Tunable Filter (BTF) and a scanning Fabry-Perot tunable filter. 48 holographic gratings
photoinscripted helicoidally in a doped glass cylinder and preceded by 4 tunable BTF are used to study 52 emission lines
selected between the main OH night sky lines. The Smart Tunable Filter offers the advantage to be an "opto-ecological"
system providing a complete separation between spectral and spatial information avoiding problems from image slicing
and slit effects. The design can fully operate at cryogenic temperatures for IR purpose. The Fabry-Perot mode operates at
a spectral resolution of 5000 and can be removed to provide a 100 spectral resolution over the 48 fixed gratings. Main
results obtained in laboratory from the first prototype developed in collaboration with Photon etc. Inc. are presented.
Merit factors to compare this instrument to similar ones are studied versus sciences cases.
The Carnegie Planet Finder Spectrograph: a status report
Show abstract
The Carnegie Planet Finder Spectrograph (PFS) has been constructed for use with the Magellan telescopes at
Las Campanas Observatory in Chile. PFS has been optimized for high-precision measurement of stellar radial
velocities in order to support an ongoing search for extrasolar planets. PFS uses an R4 echelle grating and a
prism cross-disperser in a Littrow arrangement to provide complete wavelength coverage between 390 and 620
nm distributed across 58 orders. Spectral resolution is 38,000 when using a 1 arcsec slit. An iodine absorption
cell is included in the pre-slit module to allow the superimposition of well-defined absorption features on the
stellar spectra. To improve velocity stability, the echelle grating is enclosed in a small vacuum tank with the
cross-dispersing prism acting as the vacuum window. The spectrograph is mounted on an invar optical bench that
is surrounded by an insulated enclosure with circulating liquid temperature control. Fabrication and assembly
have been completed, and testing will soon be underway. Delivery to Las Campanas Observatory is scheduled
for late 2008.
Design of a laboratory simulator to test exoplanet imaging polarimetry
Show abstract
Research on extrasolar planets is one of the most rapidly advancing fields of astrophysics. In just over a decade
since the discovery of the first extra-solar planet orbiting around 51 Pegasi, 289 extrasolar planets have been
discovered. This breakthrough is the result of the development of a wide range of new observational techniques
and facilities for the detection and characterisation of extrasolar planets. In Utrecht we are building the Extreme
Polarimeter (ExPo) to image extra-solar planets and circumstellar environments using polarimetry at contrast
ratio of 10-9.
To test and calibrate ExPo, we have built a laboratory-based simulator that mimics a star with a Jupiter-like
exoplanet as seen by the 4.2m William Herschel Telescope. The star and planet are simulated using two single-mode
fibres in close proximity that are fed with a broadband arc lamp with a contrast ratio down to 10-9. The
planet is partially linearly polarized. The telescope is simulated with two lenses, and seeing can be included
with a rotating glass plate covered with hairspray. In this paper we present the scientific requirements and the
simulator design.
Influence of instrumental noise and defocus on the DIMM
Show abstract
The instrumental noise is an important factor in any measurement.
In order to evaluate the amount of seeing introduced by the
instrumental noise, we have conducted an experiment using an
artificial light source as a star. In addition, we present a study
of the defocus effect on the DIMM results. The instrumental noise
variance was measured in the laboratory for different states of
defocusing. In this paper we will present the results of these
various experiments.
LIINUS: a design study for interferometric imaging spectroscopy at the LBT
Show abstract
We present a feasible design concept and the science drivers for the proposed near-infrared interferometric integral field
spectrograph at the LBT. Combining interferometric resolution with an integral field spectrograph is a very promising
instrument concept for detailed studies down to below 10 mas angular resolution in the NIR. If approved, the instrument
will become an extension to the LINC-NIRVANA instrument, which is under construction.
In this contribution an opto-mechanical design concept has been studied in detail: that places the integral field unit into
an existing empty compartment within the LINC hardware. Several optical and mechanical challenges have been
successfully mastered, among them:
- the limitation of the achievable angular resolution due to the parallactic angle rotation versus the LBT baseline,
- the anamorphic magnification required by the LBT optics design to optimize the detector information content, and
- integrating the IFU into the existing LINC cryostat without interfering with the existing optics and mechanics.
The science program spans from solar system studies and spectroscopy of exoplanets to the black hole dynamics in the
center of our and other galaxies.
Dispersed interferometry for infrared exoplanet velocimetry
Show abstract
The TEDI (TripleSpec - Exoplanet Discovery Instrument) is the first instrument dedicated to the near infrared radial
velocity search for planetary companions to low-mass stars. The TEDI uses Externally Dispersed Interferometry (EDI), a
combination of interferometry and multichannel dispersive spectroscopy. We have joined a white-light interferometer
with the Cornell TripleSpec (0.9 - 2.4 μm) spectrograph at the Palomar Observatory 200" telescope and begun an
experimental program to establish both the experimental and analytical techniques required for precision IR velocimetry
and the Doppler-search for planets orbiting low mass stars and brown dwarfs.
Gemini helium closed cycle cooling system
Show abstract
The Gemini Observatory presents the Helium Closed Cycle Cooling System that provides cooling capacity at cryogenic
temperatures for instruments and detectors. It is implemented by running three independent helium closed cycle cooling
circuits with several banks of compressors in parallel to continuously supply high purity helium gas to cryocoolers
located about 100-120 meters apart. This poster describes how the system has been implemented, the required helium
pressures and gas flow to reach cryogenic temperature, the performance it has achieved, the helium compressors and
cryocoolers in use and the level of vibration the cryocoolers produce in the telescope environment. The poster also
describes the new technology for cryocoolers that Gemini is considering in the development of new instruments.
Optical design of the SCUBA-2 IFTS
Show abstract
An Imaging Fourier Transform Spectrometer (IFTS), named FTS-2, is being developed by the University of Lethbridge
for use with the SCUBA-2 sub-millimeter bolometric camera on the James Clerk Maxwell Telescope (JCMT). The FTS-2 optical model was developed and optimized in Zemax by the Institut National d'Optique (INO) to maximize the FOV
and efficiency over a range of spectral resolutions. The IFTS has been designed as a folded system including corner
cubes in the interferometer moving mirror, and extended polynomial surfaces in the interferometer folding mirrors. The
instrument design for FTS-2 is described elsewhere; here we present an analysis of the modeled performance of the IFTS
in terms of achievable Field Of View (FOV), spot pattern and vignetting, at Zero Path Difference (ZPD) and for the 2
resolution modes. The predicted imaging performance is compared to that of the SCUBA-2 camera alone.
Technical improvements and performances of SpIOMM: an imaging Fourier transform spectrometer for astronomy
Show abstract
We present the most recent technical improvements on SpIOMM, an Imaging Fourier Transform Spectrometer (IFTS)
attached to the 1.6 telescope of the Mont Megantic Observatory. The recent development of SpIOMM demonstrates that
the concept of IFTS for ground telescopes is a promising astronomical 3D spectroscopy technique for multi-object
spectroscopy and multi-band imaging. SpIOMM has been developed through a collaboration between Universite Laval
and the industry (ABB Bomem). It is designed for optical observations from the near UV (350 nm) to the near IR (850
nm) with variable spectral resolution. The circular FOV of the instrument covers 12' in diameter. We have recently
improved the servo system algorithm which now controls the mirror displacement and alignment at a rate of ~7kHz.
Hardware improvements to the servo and the metrology system will be described along with their impacts on
performance in the laboratory and in observing conditions. The instrument has successfully been operated at the 1.6
meter telescope this year using the revised control systems and acquired several datacubes. We will discuss some issues
regarding the sensitivity to environmental conditions implied by the use of such an instrument. An overview of the
datacube reduction procedure will show some solutions proposed for observational problems encountered that affect the
quality of the data such as sky transmission variations, wind, changing gravity vector and temperature.
Science results from the imaging Fourier transform spectrometer SpIOMM
Show abstract
SpIOMM is an imaging Fourier transform spectrometer designed to obtain the visible range (350 - 850 nm) spectrum of
every light source in a circular field of view of 12 arcminutes in diameter. Attached to the 1.6-m telescope of the
Observatoire du Mont Megantic in southern Quebec. We present here some results of three successful observing runs in
2007, which highlight SpIOMM's capabilities to map emission line objects over a very wide field of view and a broad
spectral range. In particular, we discuss data cubes from the planetary nebula M27, the supernova remnants NGC 6992
and M1, the barred spiral galaxy NGC7479, as well as Stephan's quintet, and interacting group of galaxies.
Current status of the HETDEX fiber optic support system
Show abstract
The Hobby-Eberly Telescope Dark Energy eXperiment [HETDEX] will employ over 43,000 optical fibers to feed light
to 192 Visible Integral-Field Replicable Unit Spectrographs [VIRUS]. Each VIRUS instrument is fed by 224 fibers. To
reduce cost, the spectrographs are combined into pairs; thus, two bundles of 224 fibers are combined into a single
Integral Field Unit [IFU] of 448 fibers. On the input end the fibers are arranged in a square 'dense-pack' array at the
HET focal surface. At the output end the IFU terminates in two separate linear arrays which provide entry slits for each
spectrometer unit. The IFU lengths must be kept to an absolute minimum to mitigate losses; however, consideration of
overall project cost and duration of the science mission have resulted in the generation of two competing concepts.
Multiple axes of motion are imposed on the IFUs as they span the shortest distance from the focal surface to each
VIRUS unit. Arranging and supporting 96 IFUs, that have a total mass over 450 kg, in a manner that is compatible with
these complex translations, together with the management of accompanying forces on the tracking mechanism of the
HET, presents a significant technical challenge, which is further compounded by wind buffeting. The longer IFU
concept is favored due to overall project cost, but requires tests to assure that the fibers can withstand forces associated
with a height differential of 16.25 meters without FRD losses or breakage.
A multi-instrument focal station for a 2m-class robotic telescope
Show abstract
The design of a multi-instrument Nasmyth port for a 2m class telescope, located near Munich, Germany is
presented in this paper. A three channel optical and infrared camera will be located at this Nasmyth focus
together with an IFU spectrograph, a high resolution Echelle spectrograph, and a Shack-Hartmann sensor for
instrument alignment. Fast switching between the instruments and compact design in a small dome are boundary
conditions of the project.
Precise guiding and acquisition is made possible for all instruments. Calibration sources are fed to the fiber
coupled instruments using a built in telescope simulator.
L-band orthomode transducer for the Sardinia Radio Telescope
Show abstract
We describe the design, construction, and characterization results of a compact L-band (1.3-1.8 GHz) Orthomode
Transducer (OMT) for the Sardinia Radio Telescope (SRT), a 64 m diameter telescope which is being built in the
Sardinia island, Italy. The OMT consists of three distinct mechanical parts connected through ultra low loss coaxial
cables: a turnstile junction and two identical 180° hybrid power combiners. The turnstile junction is based on a circular
waveguide input (diameter of 190 mm,) and on four WR650 rectangular waveguide cavities from which the RF signals
are extracted using coaxial probes. The OMT was optimized using a commercial 3D electromagnetic simulator. The
main mechanical part of the turnstile junction was machined out of an Aluminum block whose final external shape is a
cylinder with diameter 450 mm and height 98 mm.
From 1.3 to 1.8 GHz the measured reflection coefficient was less than -22 dB, the isolation between the outputs was less
than -45 dB, and the cross polarization was less than -50 dB for both polarization channels.
MONSOON image acquisition system: control techniques for application to the orthogonal transfer array detectors
Show abstract
The MONSOON Detector Controller has successfully demonstrated the ability to control the complex image acquisition
and real time processing required to achieve quality science performance from the Orthogonal Transfer Array (OTA)
detector technology. A mosaic of four OTA detectors has been used to track multiple guide stars and apply charge shift
corrections to compensate for real time image motion. The control algorithms required to achieve this have been
embedded and distributed within the MONSOON controller to reduce the control loop latency and improve correction
efficiency. This paper highlights the flexibility of the MONSOON architecture in supporting the many roles required by
applications of scientific detectors.
A global SOLIS vector spectromagnetograph (VSM) network
Show abstract
Understanding the Sun's magnetic field related activity is far from complete as reflected in the limited ability to make
accurate predictions of solar variability. To advance our understanding of solar magnetism, the National Solar
Observatory (NSO) constructed the Synoptic Optical Long-term Investigations of the Sun (SOLIS) suite of instruments
to conduct high precision optical measurements of processes on the Sun whose study requires sustained observations
over long time periods. The Vector Spectromagnetograph (VSM), the principal SOLIS instrument, has been in operation
since 2003 and obtains photospheric vector data, as well as photospheric and chromospheric longitudinal magnetic field
measurements. Instrument performance is being enhanced by employing new, high-speed cameras that virtually freeze
seeing, thus improving sensitivity to measure the solar magnetic field configuration. A major operational goal is to
provide real-time and near-real-time data for forecasting space weather and increase scientific yield from shorter
duration solar space missions and ground-based research projects. The National Solar Observatory proposes to build two
near-duplicates of the VSM instrument and place them at international sites to form a three-site global VSM network.
Current electronic industry practice of short lifetime cycles leads to improved performance and reduced acquisition costs
but also to redesign costs and engineering impacts that must be minimized. The current VSM instrument status and
experience gained from working on the original instrument is presented herein and used to demonstrate that one can
dramatically reduce the estimated cost and fabrication time required to duplicate and commission two additional
instruments.