Data analysis software for the IBIS/PICsIT high-energy detector on INTEGRAL

Abstract

The INTEGRAL gamma-ray observatory is due to be launched in October 2002 on a Proton rocket from the Russian base in Baikonur in Kazakhstan. Its scientific payload contains two main instruments on board, one dedicated to spectrometry (SPI) and with moderate imaging capabilities, and the other (IBIS) designated to produce high angular resolution images with moderate energy resolution, in addition to X-ray and Optical monitors. The IBIS telescope itself consists of two main subsystem: a low energy (15 keV - 1 MeV) detector (ISGRI) and a plane (PICsIT) working at higher energies (170 keV - 10 MeV). Both these instruments use the same coded aperture mask in order to create images of the sky over the entire energy range with a resolution of 12 arcminutes and point source location accuracy down to tens of arcseconds for the strongest sources. The data from the satellite will be trasmitted to the INTEGRAL Science Data Centre (ISDC) located near Geneva for initial processing and distribution of the analysis results. The quantity of data is large, and each observation will typically consist of many individual pointings around the target, which will then be summed together. This allows a reduction of systematic effects in the creation of the spectral imaging images. Herein we describe the data structure of the PICsIT instrument from raw low-level data through to the high-level scientific products, indicating how the data sets are used to obtain images and spectra for celestial gamma-ray sources.