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 de tectors: three pointed-mode proportional counters (PPC's) 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 brigh t X-ray sources and X-ray transients. Ln stellar mode;the PPC's observe sev eral 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 ground station. The system ha s been working Kell from the day the IXAE was commissioned. The processing electronics system for PPC's, its interfaces, and the in-orbit instrument p erformance are described in this paper. Some results of the painted mode ob servations are also presented.