The processing electronics system for the pointed mode operation of IXAE on the Indian satellite IRS-P3.

Indian Remote Sensing Satellite-P3 (IRS-P3: 1996-017A) was launched into a near-Earth, polar, Sun-synchronous orbit by India's Polar Satellite Launch Vehicle (PSLV-D3) on March 21, 1996. The Indian X-ray Astronomy Experiment (IXAE) is one of the prime payloads onboard IRS-P3. IXAE has two sets of detectors: three pointed-mode proportional counters (PPCs) and one X-ray Sky Monitor (XSM). IRS-P3 is configured to operate in two modes, namely, Earth-pointing mode and stellar-pointing mode. In Earth-pointing mode the remote sensing payloads are in operation; in addition, XSM maps the sky for bright X-ray sources and X-ray transients. In stellar mode, the PPCs observe several Galactic, bright X-ray, and extragalactic sources. The microprocessor-based processing electronics system was designed and developed for PPC data-handling and telemetering the stored data to the ground station. The system has been working well from the day the IXAE was commissioned. The processing electronics system for the PPCs, its interfaces, and the in-orbit instrument performance are described. Some results of the pointed mode observations are also presented.