AstroSat makes rare discovery
AstroSat, India's first multi- wavelength satellite, has detected an extreme ultraviolet (UV) light from a galaxy which is 9.3 billion light-years away from Earth, the Inter-University Centre for Astronomy and Astrophysics (IUCAA) said on 24 August 2020. A release from the Pune-based Inter-University Centre for Astronomy and Astrophysics said a global team led by IUCAA scientists have achieved the major breakthrough. Indias first multi-wavelength satellite, which has five unique X-ray and ultraviolet telescopes working in tandem, AstroSat, has detected extreme-UV light from a galaxy, called AUDFs01, 9.3 billion light-yearsaway from Earth.
- The discovery was made by an international team of astronomers led by Dr Kanak Saha, associate professor of astronomy at the IUCAA, and published on August 24 by 'Nature Astronomy', the release said.
- This team comprised scientists from India, France, Switzerland, the USA, Japan and The Netherlands.
- Saha and his team observed the galaxy, which is located in the Hubble Extreme Deep field, through AstroSat. These observations lasted for more than 28 hours in October 2016.
- But it took nearly two years since then to carefully analyse the data to ascertain that the emission is indeed from the galaxy. Since UV radiation is absorbed by Earths atmosphere, it has to be observed from space.
- Earlier, NASAs Hubble Space Telescope (HST), significantly larger than UVIT (UV imaging telescope), did not detect any UV emission (with energy greater than 13.6 eV) from this galaxy because it is too faint.
- AstroSat/UVIT was able to achieve this unique feat because the background noise in the UVITdetector is much less than the ones on HST, said the release quoting Saha.
- Saha said they knew it would be an uphill task to convince the international community that UVIT has recorded extreme-UV emission from this galaxy when more powerful HST has not.
- AstroSat is the first dedicated Indian astronomy mission aimed at studying celestial sources in X-ray, optical and UV spectral bands simultaneously.
- The payloads cover the energy bands of Ultraviolet (Near and Far), limited optical and X-ray regime (0.3 keV to 100keV).
- One of the unique features of AstroSat mission is that it enables the simultaneous multi-wavelength observations of various astronomical objects with a single satellite.
- AstroSat with a lift-off mass of 1515 kg was launched on September 28, 2015 into a 650 km orbit inclined at an angle of 6 deg to the equator by PSLV-C30 from Satish Dhawan Space Centre, Sriharikota. The minimum useful life of the AstroSat mission is expected to be 5 years.
- After injection into Orbit, the two solar panels of AstroSat were automatically deployed in quick succession.
- The spacecraft control centre at Mission Operations Complex (MOX) of ISRO Telemetry, Tracking and Command Network (ISTRAC), Bengaluru manages the satellite during its entire mission life.