ASTROSAT, India's first dedicated astronomy space mission was launched on September 28, 2015. The Large Area X-ray Proportional Counter (LAXPC) is one of the major payloads on ASTROSAT. A cluster of three co-aligned identical LAXPC detectors provide large area of collection .The large detection volume (15 cm depth) filled with mixture of xenon gas (90(%) and methane (10%) at ~ 2 atmospheres pressure, results in detection efficiency greater than 50%, above 30 keV. The LAXPC instrument is best suited for X-ray timing and spectral studies. It will provide the largest effective area in 3-80 keV range among all the satellite missions flown so far worldwide and will remain so for the next 5-10 years. The LAXPC detectors have been calibrated using radioactive sources in the laboratory. GEANT4 simulation for LAXPC detectors was carried out to understand detector background and its response. The LAXPC instrument became fully operational on 19th October 2015 for the first time in space. We have performed detector calibration in orbit. The LAXPC instrument is functioning well and has achieved all detector parameters proposed initially. In this paper, we will describe LAXPC detector calibration in lab as well as in orbit along with first results.
ASTROSAT is India’s first astronomy satellite that will carry an array of instruments capable of simultaneous observations in a broad range of wavelengths: from the visible, near ultraviolet (NUV), far-UV (FUV), soft X-rays to hard X-rays. There will be five principal scientific payloads aboard the satellite: (i) a Soft X-ray Telescope (SXT), (ii) three Large Area Xenon Proportional Counters (LAXPCs), (iii) a Cadmium-Zinc-Telluride Imager (CZTI), (iv) two Ultra-Violet Imaging Telescopes (UVITs) one for visible and near-UV channels and another for far-UV, and (v) three Scanning Sky Monitors (SSMs). It will also carry a charged particle monitor (CPM). Almost all the instruments have qualified and their flight models are currently in different stages of integration into the satellite structure in ISRO Satellite Centre. ASTROSAT is due to be launched by India’s Polar Satellite Launch Vehicle (PSLV) in the first half of 2015 in a circular 600 km orbit with inclination of ~6 degrees, from Sriharikota launching station on the east coast of India. A brief description of the design, construction, capabilities and scientific objectives of all the main scientific payloads is presented here. A few examples of the simulated observations with ASTROSAT and plans to utilize the satellite nationally and internationally are also presented.