AstroSat

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AstroSat
Astrosat-1 in deployed configuration 001.png
Mission type Space telescope
Operator ISRO
COSPAR ID 2015-052A OOjs UI icon edit-ltr-progressive.svg
SATCAT no. 40930
Website astrosat.iucaa.in
Mission durationPlanned: 5 years
Elapsed : 8 years, 9 months, 19 days
Spacecraft properties
SpacecraftAstroSat
Launch mass1,513 kg (3,336 lb)
Start of mission
Launch dateSeptember 28, 2015 (2015-09-28) [1] [2]
Rocket PSLV-C30
Launch site Satish Dhawan Space Centre First Launch Pad
ContractorISRO
Orbital parameters
Reference system Geocentric
Regime Near-equatorial
Semi-major axis 7020 km
Perigee altitude 643.5 km
Apogee altitude 654.9 km
Inclination 6.0°
Period 97.6 min
Main
WavelengthsFar Ultraviolet to hard X-ray
Instruments
UVIT
SXT
LAXPC
CZTI
SSM
CPM
AstroSat-2  
 

AstroSat is India's first dedicated multi-wavelength space telescope. It was launched on a PSLV-XL on 28 September 2015. [1] [2] With the success of this satellite, ISRO has proposed launching AstroSat-2 as a successor for AstroSat. [3]

Contents

Overview

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. [4]

A number of astronomy research institutions in India, and abroad have jointly built instruments for the satellite. Important areas requiring coverage include studies of astrophysical objects ranging from nearby Solar System objects to distant stars and objects at cosmological distances; timing studies of variables ranging from pulsations of hot white dwarfs to those of active galactic nuclei can be conducted with AstroSat as well, with time scales ranging from milliseconds to days.

AstroSat is a multi-wavelength astronomy mission on an IRS-class satellite into a near-Earth, equatorial orbit. The five instruments on board cover the visible (320–530 nm), near UV (180–300 nm), far UV (130–180 nm), soft X-ray (0.3–8 keV and 2–10 keV) and hard X-ray (3–80 keV and 10–150 keV) regions of the electromagnetic spectrum.

The sanctioned cost of Astrosat was ₹177.85 crore. [5] Astrosat was successfully launched on 28 September 2015 from the Satish Dhawan Space Centre on board a PSLV-XL vehicle at 10:00AM.

Mission

Artist's conception of a binary star system with one black hole and one main sequence star Accretion disk.jpg
Artist's conception of a binary star system with one black hole and one main sequence star
Tilted view of Astrosat Tilted view of Astrosat-1 with folded solar-arrays.jpg
Tilted view of Astrosat

AstroSat is a proposal-driven general purpose observatory, with main scientific focus on:

AstroSat performs multi-wavelength observations covering spectral bands from radio, optical, IR, UV, and X-ray wavelengths. Both individual studies of specific sources of interest and surveys are undertaken. While radio, optical, and IR observations would be coordinated through ground-based telescopes, the high energy regions, i.e., UV, X-ray and visible wavelength, would be covered by the dedicated satellite-borne instrumentation of AstroSat. [6]

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 the X-ray, with 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.

The observatory will also carry out:

In particular, the mission will train its instruments at active galactic nuclei, which are believed to contain super-massive black holes. [8]

Payloads

Astrosat folded large.png

The scientific payload contains six instruments.

Ground support

The Ground Command and Control Center for Astrosat is the ISRO Telemetry, Tracking and Command Network (ISTRAC) at Bangalore, India. Command and control of the spacecraft, and scientific data downloads is possible during every visible pass over Bangalore. 10 out of 14 orbits per day are visible to the ground station. [12] The satellite is capable of gathering 420 gigabits of data every day that can be downloaded during the 10 visible orbits by the Tracking and Data receiving center of ISRO in Bangalore. A third 11-meter antenna at the Indian Deep Space Network (IDSN) became operational in July 2009 to track Astrosat.

AstroSat Support Cell

ISRO has set up a support cell for AstroSat at IUCAA, Pune. A MoU was signed between ISRO and IUCAA in May 2016. The support cell has been set up to give opportunity to the scientific community in making proposals on processing and usage of AstroSat data. The support cell will provide necessary resource materials, tools, training and help to the guest observers. [13]

Participants

The Astrosat project is a collaborative effort of many different research institutions. The participants are:

Timeline

One of the first images takes by Astrosat-1, The Near-UV (200-300 nm) and Far-UV (130-180 nm) images were captured by Ultra-Violet Imaging Telescope(UVIT) AstroSatPicO1 medium.webp
One of the first images takes by Astrosat-1, The Near-UV (200-300 nm) and Far-UV (130-180 nm) images were captured by Ultra-Violet Imaging Telescope(UVIT)

Results

A gamma-ray burst was detected by Astrosat on 5 January 2017. There was a confusion whether this event was related to the gravitational wave signal detected by LIGO from the black hole merger event GW170104 on 4 January 2017. [21] Astrosat helped in distinguishing between the two events. The gamma-ray burst from 4 January 2017 was identified as a distinct supernova explosion that would form a black hole. [21]

Astrosat also captured the rare phenomenon of a 6 billion year old small star or blue straggler feeding off and sucking out the mass and energy of a bigger companion star. [22]

On 31 May 2017, Astrosat, Chandra X-ray Observatory and Hubble Space Telescope simultaneously detected a coronal explosion on the nearest planet-hosting star Proxima Centauri [23] [24]

On 6 November 2017 Nature Astronomy published a paper from Indian astronomers measuring the variations of X-ray polarisation of the Crab Pulsar in the Taurus constellation. [25] [26] This study was a project conducted by scientists from Tata Institute of Fundamental Research, Mumbai; the Vikram Sarabhai Space Centre, Thiruvananthapuram; ISRO Satellite Centre Bengaluru; the Inter-University Centre for Astronomy and Astrophysics, Pune; and the Physical Research Laboratory, Ahmedabad. [26]

In July 2018, Astrosat has captured an image of a special galaxy cluster that is more than 800 million light years away from Earth. Named abell 2256 the galaxy cluster is made of three separate cluster of galaxy that are all merging with one another to eventually form a single massive cluster in the future. The three massive cluster contain more than 500 galaxies and the cluster is almost 100 times larger and more than 1500 times massive as our own galaxy. [27]

On 26 September 2018, the archival data of AstroSat was publicly released. [28] As of 28 September 2018, data from AstroSat has been cited in around 100 publications in refereed journals. This figure is expected to rise after the public release of data from AstroSat. [29]

In 2019 AstroSat observed a very rare X-ray outburst in a Be/X-ray binary system RX J0209.6-7427. Only a couple of rare outbursts have been observed from this source hosting a neutron star. The last outburst was detected in 2019 after about 26 years. The accreting neutron star in this Be/X-ray binary system was found to be an ultraluminous X-ray Pulsar (ULXP) making it the second closest ULXP and the first ULXP in our neighbouring Galaxy in the Magellanic Clouds. This source is the first ULX pulsar discovered with the AstroSat mission and only the eight known ULX pulsar. [30] [31] [32]

In August 2020, AstroSat had detected extreme-UV light from a galaxy located 9.3 billion light-years away from Earth. The galaxy called AUDFs01 was discovered by a team of Astronomers led by Kanak Saha from the Inter-University Centre for Astronomy and Astrophysics, Pune. [33] [34]

In 2019 a documentary titled Indian Space Dreams on the developmental journey of Astrosat, and directed by Sue Sudbury, was released. [35]

See also

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