India’s ASTROSAT makes rare Discovery

ASTROSAT, the first multi wavelength satellite has detected extreme UV light from galaxy that 9.3 billion light years away from the Earth.


The first multi-wavelength satellite of India has five unique X-ray and UV telescopes. They detect extreme UV light from galaxies that are billion light years away from the earth. It is an IRS class satellite. IRS is Indian Remote Sensing Satellite.

The NASA Hubble Space Telescope is larger than the UV Imaging Telescope (UVIT). However, it did not detect UV emission from the galaxy as it is too faint. On the other hand, the UVIT was able to achieve the detection as the background noise in the UVIT detector is much less than that on the HST.


ASTROSAT is the first multi-wavelength space telescope of India. It was launched on September 28, 2015. With its success, ISRO is planning to launch ASTROSAT-2 as its successor.

The five major instruments on board covers soft X-ray, hard X-ray, far UV, near UV, and visible light.

Control Centres of ASTROSAT

The control centres of Astrosat are located in the following places

  • ISSDC, Bangalore: Indian space Science Data Centre. It is the primary data archive centre of Astrosat
  • ISTRAC, Bangalore: ISRO Telemetry, Tracking and Command Network. It is the ground command and control centre for Astrosat.

Achievements of ASTROSAT

The sub-dwarf class star was a mystery to astronomers since 1995. Astrosat UVIT solved the puzzle. It revealed that a sub-dwarf star is binary system, meaning there are two stars, one hot and the other cool. Sub dwarfs are of luminosity Class VI under Yerkes spectral classification system.

Stellar Classification

In astronomy, the stars are classified based on their spectral characteristics. They are as follows

  • Hypergiants
  • Supergiants
  • Bright giants
  • Giants
  • Subgiants
  • Dwarfs
  • Sub dwarfs
  • White Dwarfs