Stretched Rohini Satellite Series

The Stretched Rohini Satellite Series (SROSS) are a series of satellites developed by the Indian Space Research Organisation as follow ons to the Rohini Satellites^[1] for conducting astrophysics, Earth Remote Sensing, and upper atmospheric monitoring experiments as well as for new and novel application-oriented missions.^[2] These satellites were the payload of the developmental flights of the Augmented Satellite Launch Vehicle.^[1]

The first two satellites in the series did not make it into orbit due to launch vehicle failure. SROSS-A carried two retro-reflectors for laser tracking.^[1] SROSS-B carried two instruments; a West German Monocular Electro Optical Stereo Scanner (MEOSS) and ISRO's 20-3000keV Gamma-ray Burst Experiment (GRB).^[1]

The third, SROSS 3 (also known as SROSS C), attained a lower-than-planned orbit on 20 May 1992. The GRB monitored celestial gamma ray bursts in the energy range 20–3000 keV. SROSS C and C2 carried a gamma-ray burst (GRB) experiment and a Retarded Potential Analyzer (RPA) experiment. The GRB experiment operated from 25 May 1992 until reentry on 14 July 1992. The instrument consisted of a main and a redundant CsI(Na) scintillator operating in the energy range 20–3000 keV. The crystals were 76 mm (main) and 37 mm (redundant) in diameter. Each had a thickness of 12.5 mm. A 'burst mode' was triggered by the 100–1024 keV count rate exceeding a preset limit during a 256 or 1024 ms time integration. In this mode, 65 s of temporal and 2 s of spectral data prior to the trigger are stored, as well as the subsequent 16 s of spectral data and 204 s of temporal data. The low resolution data consists of two energy channels (20–100 keV and 100–1024 keV) from 65 s before the trigger to 204 s after the trigger in 256 ms integrations. The 20–1024 keV rates are also recorded with a 2 ms resolution for 1 s prior to 1 s after trigger and a 16 ms resolution for 1s prior to 8 s after the trigger. Energy spectra are conducted with a 124 channel PHA. Four pre-trigger spectra and 32 post-trigger spectra are recorded for every burst with a 512 ms integration time.^[3] The RPA measured temperature, density and characteristics of electrons in the Earth's ionosphere.^[1] The GRB experiment computer system used the RCA CDP1802 microprocessor.^[4]

SROSS-C2 was launched on 4 May 1994. The gamma ray burst experiments on board SROSS-C2 are an improved version of the GRB payload flown successfully on the SROSS-C satellite. The improvements include enhancements of the on-board memory and a better measurement of the background spectra after a burst event. These improvements led to the discovery of twelve candidate events detected up to 15 February 1995, out of a total of 993 triggers.^[3] The SROSS-C2 spacecraft is one of the satellites included in the Interplanetary Network^[5] The SROSS C2 satellite also used an RCA CDP1802 microprocessor for the GRB experiment.^[6]

• List of Indian satellites