India joins the list of space observatory owners after successfully launching ASTROSAT

Astrosat is India’s first dedicated astronomy satellite and was successfully launched on board the PSLV on 28 September 2015. Thereby, India joins the list of selected group of nations owning space observatory.

The 44.4 metres tall, 320 ton polar satellite vehicle’s XL variant (PSLV-XL) blasted off the first launch pad at 10am at the rocket port in Sriharikota, around 80 km from Chennai, amidst cheers of Indian space agency officials and the media assembled there.

ASTROSAT was placed almost 650 kilometres above the surface of the Earth. It is expected to have a mission life of five years.

After the success of the satellite-borne Indian X-ray Astronomy Experiment (IXAE), which was launched in 1996, the Indian Space Research Organization (ISRO) approved further development for a full-fledged astronomy satellite, Astrosat, in 2004.


With the successful launch of ASTROSAT, India gained an entry into the select club of nations having its own space observatory after the US, Japan, Russia and Europe.

The launch vehicle used to place Astrosat in orbit also carried a payload of satellites from Indonesia, Canada and the US.

This is the first time an Indian vehicle has been used to place US satellites in orbit.

Astrosat will carry out multi-wavelength observations covering spectral bands from radio, optical, IR, UV, X-ray and Gamma ray regions both for study of specific sources of interest and in survey mode. While radio, optical, IR observations would be coordinated through ground-based telescopes, the high energy regions, i.e., UV, X-rays and Gamma rays would be covered by the dedicated satellite borne instrumentation of Astrosat.


The mission would also study near simultaneous multi-wavelength data from different variable sources. In a binary system, for example, regions near the compact object emit predominantly in X-rays, the accretion disc emitting most of its light in the UV/optical waveband, whereas the mass of the donating star is brightest in the optical band.

Just over 22 minutes into the flight, the rocket slug ASTROSAT at an altitude of 650 km above the earth. Soon after, six other satellites were put into orbit and the whole mission ended in just over 25 minutes.

Astrosat is a proposal-driven general purpose observatory, with main scientific focus on:
–>Simultaneous multi-wavelength monitoring of intensity variations in a broad range of cosmic sources
–>Monitoring the X-ray sky for new transients
–>Sky surveys in the hard X-ray and UV bands
–>Broadband spectroscopic studies of X-ray binaries, AGN, SNRs, clusters of galaxies and stellar coronae
–>Studies of periodic and non-periodic variability of X-ray sources

– Spadman