CANCELED: The calibration of the Compton Spectrometer and Imager (COSI) instrument

The Compton Spectrometer and Imager (COSI) is a NASA Small Explorer Mission (SMEX) that will be launched into an equatorial low-earth orbit in 2027. The COSI instrument is a wide-field Compton telescope comprised of 16 germanium detectors that will survey the sky in the underexplored soft gamma-ray regime (0.2-5 MeV) to provide polarizations, spectrometry, and imaging of astrophysical sources. Instrument calibrations play an integral role in mission development as they are used to convert the measured detector parameters to the physical properties necessary for Compton reconstruction and to benchmark simulations. Calibrations directly impact the scientific return of the mission as the performance of the event reconstruction is limited by the accuracy to which calibrations were performed. In this work we will outline the COSI detector characterizations and instrument calibrations necessary to support COSI’s broad science goals.