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Proceedings Paper

The GREGOR dome, pathfinder for the EST dome
Author(s): Robert H. Hammerschlag; Johannes N. Kommers; Simon Visser; Felix C. M. Bettonvil; Anton G. M. van Schie; Simon J. van Leverink; Guus Sliepen; Aswin P. L. Jägers
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Paper Abstract

The completely open-foldable dome of the GREGOR telescope is a further development of the DOT dome, respectively 9 and 7 meter in diameter. New technical developments are implemented and tested at the GREGOR dome, that are important for the design of the much larger dome for the EST, which will be 28 meter in diameter. The GREGOR dome is the first with more than one clamp working simultaneously for closing the dome and bringing the membranes on the required high tension for storm resistance. The storm Delta with 245 km/h 1-minute mean maximum at the location of the GREGOR gave no problems nor did the storms afterwards. Opening and closing experiences are up to wind speeds of 90 km/h without problems. Good observing circumstances never occur with higher wind speeds. A double layer of membranes is applied in the GREGOR construction whereas the DOT dome is equipped with a single layer. Simultaneous climate measurements inside and outside the dome have proven the thermal-insulation capability of this double-layer construction. The experiences with the GREGOR showed that the elongation by tensioning of the prestrained membrane material is much lower than originally expected. In the meantime, more strong and stiff membrane material is available and applied in the EST design. As a consequence, the clamps of the EST can have a relatively much shorter length and there is no need anymore for simultaneous operation of the clamps and the main actuators in low speed with help of a frequency inverter. The clamps can close after the main bow operation is finished, which simplifies the electrical control.

Paper Details

Date Published: 13 September 2012
PDF: 18 pages
Proc. SPIE 8450, Modern Technologies in Space- and Ground-based Telescopes and Instrumentation II, 845007 (13 September 2012); doi: 10.1117/12.924953
Show Author Affiliations
Robert H. Hammerschlag, Utrecht Univ. (Netherlands)
Johannes N. Kommers, Hankom Engineering (Netherlands)
Simon Visser, Poly-Ned BV (Netherlands)
Felix C. M. Bettonvil, ASTRON (Netherlands)
Leiden Observatory (Netherlands)
Anton G. M. van Schie, Delft Univ. of Technology (Netherlands)
Simon J. van Leverink, Royal Duyvis Wiener B.V. (Netherlands)
Guus Sliepen, Institute for Solar Physics (Sweden)
Aswin P. L. Jägers, Utrecht Univ. (Netherlands)

Published in SPIE Proceedings Vol. 8450:
Modern Technologies in Space- and Ground-based Telescopes and Instrumentation II
Ramón Navarro; Colin R. Cunningham; Eric Prieto, Editor(s)

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