Letter to the Editor

In-flight calibration of the ISGRI camera

¹ Service d'Astrophysique, CEA/Saclay, France
² Insituto di Astrofisica Spaziale e Fisica cosmica, CNR, Rome, Italy
³ School of Physics and Astronomy, University of Southampton, Southampton, UK
⁴ Insituto di Astrofisica Spaziale e Fisica cosmica, CNR, Sezione di Bologna, Italy
⁵ Insituto di Astrofisica Spaziale e Fisica cosmica, CNR, Sezione di Palermo, Italy

Corresponding author: R. Terrier, rterrier@cea.fr

Received: 16 July 2003
Accepted: 10 September 2003

Abstract

ISGRI, the IBIS low energy camera (15 keV-1 MeV) on board INTEGRAL, is the first large CdTe gamma-ray imager in orbit. We present here an overview of the ISGRI in-flight calibrations performed during the first months after launch. We discuss the stability of the camera as well as the CdTe pixels response under cosmic radiation. The energy calibrations were done using lead and tungsten fluorescence lines and the calibration unit. Thermal effects and charge correction algorithm are discussed, and the resulting energy resolution is presented. The ISGRI background spatial and spectral non-uniformity is also described, and some image correction results are presented.