View source for Astronomy:AstroSat

{{Short description|Space observatory}}
{{Italic title}}
{{Use Indian English|date=December 2023}}
{{Infobox spaceflight
| name               = ''AstroSat''
| names_list         = <!--list of previous names if the spacecraft has been renamed. 
Include the dates applicable if possible, and separate each name with a linebreak. 
Omit if the spacecraft has only ever been known by one name. 
Do not include Harvard, COSPAR/NSSDC or SATCAT/NORAD/NASA designations as alternative names-->

<!--image of the spacecraft/mission-->| image              = File:Astrosat-1_in_deployed_configuration_001.png
| image_caption      = <!--image caption-->
| image_size         = 300px

<!--Basic details-->| mission_type       = [[Astronomy:Space telescope|Space telescope]]
| operator           = [[Astronomy:ISRO|ISRO]]
| COSPAR_ID          = 2015-052A
| SATCAT             = 40930
| website            = {{url|http://astrosat.iucaa.in/}}
| mission_duration   = Planned: 5 years <br/> Elapsed : {{time interval|28 September 2015|show=ymd|sep=,}}
<!--Spacecraft properties-->| spacecraft         = ''AstroSat''
| manufacturer       = <!--company or companies who built the satellite-->
| launch_mass        = {{convert|1513|kg|abbr=on}}
| dry_mass           = <!--spacecraft mass in orbit without fuel-->
| payload_mass       = <!--Mass of cargo carried by spacecraft (eg. for Space Shuttle), or total mass of instrumentation/equipment/experiments for mission-->
| dimensions         = 
| power              = <!--end-of-life power, in watts-->

<!--Launch details-->| launch_date        = {{start date|2015|09|28}}<ref name="astro15">{{cite news | url=http://www.thehindu.com/sci-tech/science/indias-eye-on-universe-ready-for-tests/article7224853.ece | title=India's eye on universe ready for tests | access-date= May 20, 2015 | newspaper=The Hindu | date=2015-05-19 | last1=s | first1=Madhumathi D. }}</ref><ref name="astrosatiucaa">{{cite web|url=http://astrosat.iucaa.in/ |title=ASTROSAT: A Satellite Mission for Multi-wavelength Astronomy |publisher=IUCAA |date=2012-04-20 |access-date=2013-09-07 |archive-url=https://web.archive.org/web/20130422111440/http://astrosat.iucaa.in/ |archive-date=2013-04-22 |url-status=live }}</ref>
| launch_rocket      = PSLV-C30
| launch_site        = [[Astronomy:Satish Dhawan Space Centre First Launch Pad|Satish Dhawan Space Centre First Launch Pad]]
| launch_contractor  = ISRO

<!--orbit parameters-->| orbit_reference    = [[Astronomy:Geocentric orbit|Geocentric]]
| orbit_regime       = [[Astronomy:Near-equatorial orbit|Near-equatorial]]
| orbit_slot         = <!--Designation of orbital position or slot, if not longitude (e.g plane and position of a GPS satellite)-->
| orbit_semimajor    = 7020&nbsp;km
| orbit_eccentricity = <!--orbital eccentricity-->
| orbit_periapsis    = 643.5&nbsp;km
| orbit_apoapsis     = 654.9&nbsp;km
| orbit_inclination  = 6.0°
| orbit_period       = 97.6&nbsp;min
| orbit_RAAN         = <!--right ascension of the ascending node-->
| orbit_arg_periapsis = <!--argument of perigee/periapsis-->
| orbit_mean_anomaly = <!--mean anomaly at epoch, only use in conjunction with an epoch value-->
| orbit_mean_motion  = <!--mean motion of the satellite, usually measured in orbits per day-->
| orbit_repeat       = <!--repeat interval/revisit time-->
| orbit_velocity     = <!--speed at which the spacecraft was travelling at epoch - only use for spacecraft with low orbital eccentricity-->
| orbit_epoch        = <!--the date at which the orbit parameters were correct-->
| orbit_rev_number   = <!--revolution number-->
| apsis              = gee

<!--Telescope parameters-->| instrument_type    = <!--converts telescope fields to suit a camera or other similar instrument-->
| telescope_name     = <!--name, if different to the satellite-->
| telescope_type     = <!--type of telescope, mirror arrangement, etc-->
| telescope_diameter = <!--diameter of telescope-->
| telescope_focal_length = <!--focal length of telescope-->
| telescope_area     = <!--collecting area-->
| telescope_wavelength = Far [[Physics:Ultraviolet|Ultraviolet]] to hard [[Astronomy:X-ray astronomy|X-ray]]
| telescope_resolution = <!--resolution of telescope-->
| instruments        = UVIT<br/>SXT<br/>LAXPC<br/>CZTI<br/>SSM<br/>CPM

<!--mission insignia or patch-->| insignia           = <!--omit the "file" prefix-->
| insignia_caption   = <!--image caption-->
| insignia_alt       = <!--image alt text-->
| insignia_size      = <!--include px/em; defaults to 180px-->
| next_mission       = [[Astronomy:AstroSat-2|AstroSat-2]]
}}

'''''AstroSat''''' is India's first dedicated multi-wavelength [[Astronomy:Space telescope|space telescope]]. It was launched on a [[Engineering:Polar Satellite Launch Vehicle#PSLV-XL|PSLV-XL]] on 28 September 2015.<ref name="astro15" /><ref name=astrosatiucaa/> With the success of this satellite, ISRO has proposed launching ''[[Astronomy:AstroSat-2|AstroSat-2]]'' as a successor for ''AstroSat''.<ref name=TOI1>[https://timesofindia.indiatimes.com/home/science/isro-plans-to-launch-indias-2nd-space-observatory/articleshow/62975636.cms Isro plans to launch India's 2nd space observatory] Times of India 19 February 2018</ref>

==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.<ref name="thehindu">{{cite news | url=http://www.thehindu.com/news/national/article3650407.ece | title=India set to launch Astrosat next year | newspaper=The Hindu | date=2012-07-18 | access-date=2013-09-07 | last1=Raj | first1=N. Gopal }}</ref>

A number of astronomy research institutions in India, and abroad have jointly built instruments for the satellite. Important areas requiring coverage include studies of [[Physics:Astrophysics|astrophysical]] objects ranging from nearby [[Astronomy:Solar System|Solar System]] objects to distant stars and objects at [[Astronomy:Cosmology|cosmological]] distances; timing studies of variables ranging from pulsations of hot [[Astronomy:White dwarf|white dwarf]]s to those of [[Active galactic nucleus|active galactic nuclei]] can be conducted with ''AstroSat'' as well, with time scales ranging from milliseconds to days.

''AstroSat'' is a multi-[[Wavelength|wavelength]] astronomy mission on an IRS-class satellite into a near-Earth, equatorial orbit.  The five instruments on board cover the [[Physics:Visible spectrum|visible]] (320–530&nbsp;nm), [[Physics:Ultraviolet|near UV]] (180–300&nbsp;nm), [[Physics:Ultraviolet|far UV]] (130–180&nbsp;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 [[Physics:Electromagnetic spectrum|electromagnetic spectrum]].

The sanctioned cost of Astrosat was ₹177.85 crore.<ref>{{Cite web |title=Launch of Astrosat |url=https://pib.gov.in/newsite/PrintRelease.aspx?relid=132222 |access-date=2023-03-03 |website=pib.gov.in}}</ref> ''Astrosat'' was successfully launched on 28 September 2015 from the [[Astronomy:Satish Dhawan Space Centre|Satish Dhawan Space Centre]] on board a [[Engineering:Polar Satellite Launch Vehicle|PSLV-XL]] vehicle at 10:00AM.

==Mission==
[[Image:Accretion disk.jpg|thumb|Artist's conception of a binary star system with one black hole and one main sequence star]]
[[File:Tilted view of Astrosat-1 with folded solar-arrays.jpg|thumb|Tilted view of Astrosat|alt=]]
''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, [[Active galactic nucleus|AGN]], [[Astronomy:Supernova remnant|SNR]]s, clusters of galaxies, and stellar coronae
* Studies of periodic and non-periodic variability of X-ray sources

''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 [[Astronomy:Astronomical survey|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''.<ref name=yin2008>{{cite web | url=http://www.yourindustrynews.com/india+plans+for+x-ray+spacecraft+2009+launch_15475.html | title=India plans for X-ray spacecraft 2009 launch | publisher=Yourindustrynews.com | date=2008-11-13 | access-date=2010-11-24 | archive-url=https://web.archive.org/web/20160303205220/http://www.yourindustrynews.com/india+plans+for+x-ray+spacecraft+2009+launch_15475.html | archive-date=2016-03-03 | url-status=dead }}</ref>

The mission would also study near simultaneous multi-wavelength data from different variable sources. In a [[Astronomy:Binary system|binary system]], for example, regions near the compact object emit predominantly in the [[Physics:X-ray|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:
* Low- to moderate-resolution [[Physics:Spectroscopy|spectroscopy]] over a wide energy band with the primary emphasis on studies of X-ray-emitting objects
* Timing studies of periodic and aperiodic phenomena in X-ray binaries
* Studies of pulsations in [[Astronomy:X-ray pulsar|X-ray pulsar]]s
* Quasi-periodic oscillations, flickering, flaring, and other variations in X-ray binaries
* Short- and long-term intensity variations in [[Active galactic nucleus|active galactic nuclei]]
* Time-lag studies in low/hard X-rays and UV/optical radiation
* Detection and study of X-ray transients.<ref>{{cite web|url=http://www.isro.org/scripts/futureprogramme.aspx |title=Welcome To Indian Space Research Organisation :: Current Programme |publisher=Isro.org |date=2009-09-23 |access-date=2010-11-24| archive-url= https://web.archive.org/web/20101125163045/http://isro.org/scripts/futureprogramme.aspx| archive-date= 25 November 2010 | url-status= live}}</ref>

In particular, the mission will train its instruments at active galactic nuclei, which are believed to contain super-massive black holes.<ref>{{cite web|url=http://kuku.sawf.org/News/57791.aspx |title=ISRO schedules Astrosat launch for 2010 |publisher=Kuku.sawf.org |date=2009-04-22 |access-date=2010-11-24 |url-status=dead |archive-url=https://web.archive.org/web/20110719054844/http://kuku.sawf.org/News/57791.aspx |archive-date=2011-07-19 }}</ref>

==Payloads==
[[Image:Astrosat folded large.png|250px|right]]
The scientific payload contains six instruments.
* The '''Ultra Violet Imaging Telescope (UVIT)''' performs imaging simultaneously in three channels: 130–180&nbsp;nm, 180–300&nbsp;nm, and 320–530&nbsp;nm. The three detectors are vacuum image intensifiers manufactured by Photek, UK.<ref name=UVITdetectors>{{cite web| title=Photek UVIT Detectors |url=http://www2.le.ac.uk/departments/physics/research/xroa/astronomical-facilities-1/world-space-observatory-4/presentations/Photek-Space%20Science%20Detector%20Capabilities.ppt/at_download/file| website=University of Leicester| access-date=18 March 2016}}</ref> The FUV detector consists of a [[Chemistry:Caesium iodide|CsI]] [[Chemistry:Photocathode|photocathode]] with a [[Chemistry:Magnesium fluoride|MgF{{sub|2}}]] input optic, the NUV detector consists of CsTe [[Chemistry:Photocathode|photocathode]] with a [[Chemistry:Fused quartz|fused-silica]] input optic and the visible detector consists of an alkali-antimonide [[Chemistry:Photocathode|photocathode]] with a [[Chemistry:Fused quartz|fused-silica]] input optic. The field of view is a circle of ~28′ diameter and the angular resolution is 1.8" for the ultraviolet channels and 2.5″ for the visible channel. In each of the three channels a spectral band can be selected through a set of filters mounted on a wheel; in addition, for the two ultraviolet channels a grating can be selected in the wheel to do slitless spectroscopy with a resolution of ~100. The primary mirror diameter of the telescope is 40&nbsp;cm.<ref name=Astrosat/>
* The '''Soft X-ray imaging Telescope (SXT)''' employs focusing optics and a deep depletion CCD camera at the focal plane to perform X-ray imaging in the 0.3–8.0 keV band. The optics will consist of 41 concentric shells of gold-coated conical foil mirrors in an approximate Wolter-I configuration (the effective area of 120&nbsp;cm<sup>2</sup>). The focal plane CCD camera will be very similar to that flown on SWIFT XRT. The CCD will be operated at a temperature of about −80&nbsp;°C by thermoelectric cooling.<ref name=Astrosat/>
* The '''Large Area X-ray Proportional Counter (LAXPC)''' covers X-ray timing and low-resolution spectral studies over a broad energy band (3–80 keV), ''Astrosat'' will use a cluster of 3 co-aligned identical Large Area X-ray Proportional Counters (LAXPCs), each with a multi-wire-multi-layer configuration and a Field of View of 1° × 1°. These detectors are designed to achieve (I) wide energy band of 3–80 keV, (II) high detection efficiency over the entire energy band, (III) narrow field of view to minimize source confusion, (IV) moderate energy resolution, (V) small internal background and (VI) long lifetime in space. The effective area of the telescope is 6000&nbsp;cm<sup>2</sup>.<ref name=Astrosat/>
* The '''Cadmium Zinc Telluride Imager (CZTI)''' is a hard X-ray imager. It will consist of a Pixellated Cadmium-Zinc-Telluride detector array of 500&nbsp;cm<sup>2</sup> effective area and the energy range from 10 to 150&nbsp;kev.<ref name=Astrosat/> The detectors have a detection efficiency close to 100% up to 100 keV, and have a superior energy resolution (~2% at 60 keV) compared to scintillation and proportional counters. Their small pixel size also facilitates medium resolution imaging in hard x-rays. The CZTI will be fitted with a two dimensional [[Astronomy:Coded aperture|coded mask]], for imaging purposes. The sky brightness distribution will be obtained by applying a deconvolution procedure to the shadow pattern of the coded mask recorded by the detector. Apart from spectroscopic studies, CZTI would be able to do sensitive polarization measurements for bright galactic X-ray sources in 100–300 keV.<ref name=cztipol>{{cite journal|last1=Chattopadhyay|first1=T.|last2=Vadawale|first2=S.V.|last3=Rao|first3=A. R.|last4=Sreekumar|first4=S.|last5=Bhattacharya|first5=D.|title=Prospects of hard X-ray polarimetry with Astrosat-CZTI|journal=Experimental Astronomy|date=2014-05-09|volume=37|issue=3|pages=555–577|doi=10.1007/s10686-014-9386-1|bibcode = 2014ExA....37..555C |s2cid=42864309}}</ref>
* The '''Scanning Sky Monitor (SSM)''' consists of three position sensitive proportional counters, each with a one-dimensional coded mask, very similar in design to the  All Sky Monitor on NASA's [[Astronomy:Rossi X-ray Timing Explorer|RXTE satellite]]. The gas-filled proportional counter will have resistive wires as anodes. The ratio of the output charge on either ends of the wire will provide the position of the x-ray interaction, providing an imaging plane at the detector. The coded mask, consisting of a series of slits, will cast a shadow on the detector, from which the sky brightness distribution will be derived.
* The '''Charged Particle Monitor (CPM)''' will be included as a part of ''Astrosat'' payloads to control the operation of the LAXPC, SXT and SSM. Even though the orbital inclination of the satellite will be 8 deg or less, in about 2/3 of the orbits, the satellite will spend a considerable time (15–20 minutes) in the [[Astronomy:South Atlantic Anomaly|South Atlantic Anomaly]] (SAA) region which has high fluxes of low energy protons and electrons. The high voltage will be lowered or put off using data from CPM when the satellite enters the SAA region to prevent damage to the detectors as well as to minimize ageing effect in the Proportional Counters.

==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.<ref>{{Cite web | url=http://astrosat.iucaa.in/ | title=ASTROSAT &#124; astrosat}}</ref> 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 [[Engineering:Indian Deep Space Network|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 [[Organization:Inter-University Centre for Astronomy and Astrophysics|IUCAA]], Pune. A [[Finance:Memorandum of understanding|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.<ref>{{Cite web |title=AstroSat Support Cell (ASC) has been Set up at IUCAA, Pune - ISRO |url=https://www.isro.gov.in/pslv-c30-astrosat-mission/astrosat-support-cell-asc-has-been-set-iucaa-pune |access-date=2022-09-05 |website=www.isro.gov.in}}</ref>

== Participants ==
The ''Astrosat'' project is a collaborative effort of many different research institutions. The participants are:
{{Div col |colwidth=25em}}

* Indian Space Research Organization
* Tata Institute of Fundamental Research, {{wipe|Mumbai}}
* [[Organization:Indian Institute of Astrophysics|Indian Institute of Astrophysics]], Bangalore
* [[Organization:Raman Research Institute|Raman Research Institute]], Bangalore
* [[Organization:Inter-University Centre for Astronomy and Astrophysics|Inter-University Centre for Astronomy and Astrophysics]], Pune
* [[Organization:Physical Research Laboratory|Physical Research Laboratory]], Ahmedabad
* [[Organization:Bhabha Atomic Research Centre|Bhabha Atomic Research Centre]], {{wipe|Mumbai}}
* S.N. Bose National Centre for Basic Sciences, [[Place:Kolkata|Kolkata]]
* Presidency University, Kolkata
* [[Organization:Canadian Space Agency|Canadian Space Agency]]
* [[Organization:University of Leicester|University of Leicester]]<ref>{{cite web|url=http://www.indodaily.com/reports/India_Works_With_University_Of_Leicester_On_First_National_Astronomy_Satellite_999.html |title=India Works With University Of Leicester On First National Astronomy Satellite |publisher=Indodaily.com |access-date=2010-11-24}}</ref>
{{div col end}}

==Timeline==

[[File:AstroSatPicO1 medium.webp|thumb|right|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)]]
* 29 Sep 2020: The satellite completed its mission life of 5 years and will continue to remain operational for many years.<ref>{{cite web|url=https://www.hindustantimes.com/science/india-s-space-telescope-completes-5-year-mission-life-will-continue-to-function-isro-chief/story-cqwBCQyVTzHu1B8SKsmfCK.html|title=India's space telescope completes 5-year mission life, will continue to function: ISRO chief|publisher=Hindustan Times|date=29 September 2020}}</ref>
* 28 Sep 2018: The satellite has completed 3 years since its launch on 2015. It has observed over 750 sources and resulted in close to 100 publications in peer-reviewed journals.<ref>{{Cite web|url=https://www.isro.gov.in/update/28-sep-2018/three-years-of-astrosat|title=Three years of AstroSat – ISRO|website=www.isro.gov.in|language=en|access-date=2018-09-28|archive-date=2019-08-30|archive-url=https://web.archive.org/web/20190830213436/http://isro.gov.in/update/28-sep-2018/three-years-of-astrosat|url-status=dead}}</ref>
*15 April 2016: The satellite has completed its performance verification and started its operations.<ref name="astrosat_iucaa">{{cite web | url=http://www.isro.gov.in/pslv-c30-astrosat-mission/astrosat-support-cell-asc-has-been-set-iucaa-pune | title=AstroSat Support Cell (ASC) has been Set up at IUCAA, Pune | publisher=isro.gov.in | work=Indian Space Research Organisation | access-date=May 23, 2016 | archive-date=May 24, 2022 | archive-url=https://web.archive.org/web/20220524040851/https://www.isro.gov.in/pslv-c30-astrosat-mission/astrosat-support-cell-asc-has-been-set-iucaa-pune | url-status=dead }}</ref>
* 28 Sep 2015: ASTROSAT has been successfully launched into orbit.<ref>{{cite news|url=http://www.isro.gov.in/pslv-c30-astrosat-mission/pslv-c30-astrosat-launch-live-webcast|title=PSLV-C30/ASTROSAT Launch Live Webcast|access-date=28 September 2015|date=28 September 2015|work=Indian Space Research Organization|archive-date=10 December 2015|archive-url=https://web.archive.org/web/20151210150952/http://www.isro.gov.in/pslv-c30-astrosat-mission/pslv-c30-astrosat-launch-live-webcast|url-status=dead}}</ref>
* 10 Aug 2015: All tests passed. Pre-shipment review successfully completed.<ref name=Astrosat>{{cite web|url=http://astrosat.iucaa.in|title=ASTROSAT|access-date=28 September 2015|publisher=Indian Space Research Organization}}</ref>
* 24 July 2015: Thermovac completed. Solar panels attached. Start of final vibration tests.<ref name=Astrosat/>
* May 2015 : The integration of ''Astrosat'' is complete and final tests are under way. ISRO issued a press release stating that "The satellite is planned to be launched during the second half of 2015 by PSLV C-34 to a 650 km near equatorial orbit around the Earth."<ref>{{cite web|title=ASTROSAT crossed a major milestone – Spacecraft fully assembled and tests initiated|url=http://www.isro.gov.in/astrosat-crossed-major-milestone-%E2%80%93-spacecraft-fully-assembled-and-tests-initiated|website=ISRO|access-date=22 May 2015|archive-date=23 December 2015|archive-url=https://web.archive.org/web/20151223213458/http://www.isro.gov.in/astrosat-crossed-major-milestone-%E2%80%93-spacecraft-fully-assembled-and-tests-initiated|url-status=dead}}</ref>
* April 2009 : Scientists from Tata Institute of Fundamental Research (TIFR) have completed the developmental phase of complex science payloads and have begun integrating them before delivery of the 1,650&nbsp;kg satellite ''Astrosat''. The challenges in the design of payloads and Attitude Control System have been overcome and in a recent review committee meeting, it was decided that the delivery of the payload to the ISRO Satellite Centre will begin from the middle of 2009 and continue until early 2010 to enable the launch of ASTROSAT in 2010 using ISRO workhorse PSLV-C34.<ref>{{cite web|url=http://www.livemint.com/2009/04/22123907/ASTROSAT-to-be-launched-in-mid.html |title=ASTROSAT to be launched in mid-2010 – Technology |publisher=livemint.com |date=2009-04-22 |access-date=2010-11-24}}</ref>

==Results==
A [[Astronomy:Gamma-ray burst|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 [[Astronomy:LIGO|LIGO]] from the black hole merger event [[Astronomy:GW170104|GW170104]] on 4 January 2017.<ref name="astro_gamma">{{Cite news |url=http://www.thehindu.com/sci-tech/science/astrosat-rules-out-afterglow-in-black-hole-merger/article19094393.ece |title=AstroSat rules out afterglow in black hole merger|newspaper=The Hindu|date=2017-06-17|last1=Desikan|first1=Shubashree}}</ref> ''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.<ref name="astro_gamma"/>

''Astrosat'' also captured the rare phenomenon of a 6 billion year old small star or [[Astronomy:Blue straggler|blue straggler]] feeding off and sucking out the mass and energy of a bigger companion star.<ref name="astro_vampire">{{Cite web |url=http://indianexpress.com/article/technology/tech-news-technology/vampire-star-caught-in-the-act-by-indian-space-observatory-4498660/ |title='Vampire' star caught in the act by Indian space observatory ASTROSAT|date=2017-01-30}}</ref>

On 31 May 2017, ''Astrosat'', [[Astronomy:Chandra X-ray Observatory|Chandra X-ray Observatory]] and [[Astronomy:Hubble Space Telescope|Hubble Space Telescope]] simultaneously detected a [[Astronomy:Stellar corona|coronal]] explosion on the nearest planet-hosting star [[Astronomy:Proxima Centauri|Proxima Centauri]]<ref>{{Cite web|url=http://www.tifr.res.in/TSN/news_detail.php?id=124|title=News Detail {{!}} TIFR|website=www.tifr.res.in|language=en|access-date=2017-07-20}}</ref><ref>{{Cite web|url=http://astrosat-ssc.iucaa.in/?q=press-release:Astrosat,%20Chandra%20and%20Hubble%20Space%20Telescope|title=Press Release: Astrosat, Chandra and Hubble Space Telescope simultaneously detect a coronal explosion on the nearest planet-hosting star {{!}} ASTROSAT SCIENCE SUPPORT CELL|website=astrosat-ssc.iucaa.in|language=en|access-date=2017-07-20}}</ref>

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.<ref>{{cite journal | url=https://www.nature.com/articles/s41550-017-0293-z | doi=10.1038/s41550-017-0293-z | title=Phase-resolved X-ray polarimetry of the Crab pulsar with the AstroSat CZT Imager | year=2017 | last1=Vadawale | first1=S. V. | last2=Chattopadhyay | first2=T. | last3=Mithun | first3=N. P. S. | last4=Rao | first4=A. R. | last5=Bhattacharya | first5=D. | last6=Vibhute | first6=A. | last7=Bhalerao | first7=V. B. | last8=Dewangan | first8=G. C. | last9=Misra | first9=R. | last10=Paul | first10=B. | last11=Basu | first11=A. | last12=Joshi | first12=B. C. | last13=Sreekumar | first13=S. | last14=Samuel | first14=E. | last15=Priya | first15=P. | last16=Vinod | first16=P. | last17=Seetha | first17=S. | journal=Nature Astronomy | volume=2 | pages=50–55 | s2cid=256708500 }}</ref><ref name="TOI201711">[https://timesofindia.indiatimes.com/home/science/indias-space-observatory-accomplishes-x-ray-polarisation/articleshow/61535714.cms India's space observatory accomplishes X-ray polarisation] Times of India 6 November 2017</ref> This study was a project conducted by scientists from Tata Institute of Fundamental Research, Mumbai; the [[Company:Vikram Sarabhai Space Centre|Vikram Sarabhai Space Centre]], Thiruvananthapuram; ISRO Satellite Centre Bengaluru; the [[Organization:Inter-University Centre for Astronomy and Astrophysics|Inter-University Centre for Astronomy and Astrophysics]], Pune; and the [[Organization:Physical Research Laboratory|Physical Research Laboratory]], Ahmedabad.<ref name="TOI201711" />

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.<ref>{{Cite news | url=https://timesofindia.indiatimes.com/home/science/isros-astrosat-captures-image-of-galaxy-cluster-800-million-light-years-away/articleshow/64836364.cms | title=Isro's Astrosat captures image of galaxy cluster 800 million light years away - Times of India| website=The Times of India| date=3 July 2018}}</ref>

On 26 September 2018, the archival data of AstroSat was publicly released.<ref>{{Cite web|url=https://www.isro.gov.in/update/26-sep-2018/archival-data-of-astrosat-released|title=Archival Data of AstroSat released - ISRO|website=www.isro.gov.in|access-date=2019-08-03|archive-date=2022-07-15|archive-url=https://web.archive.org/web/20220715184540/https://www.isro.gov.in/update/26-sep-2018/archival-data-of-astrosat-released|url-status=dead}}</ref> 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.<ref>{{Cite web|url=https://www.isro.gov.in/update/28-sep-2018/three-years-of-astrosat|title=Three years of AstroSat - ISRO|website=www.isro.gov.in|access-date=2019-08-03|archive-date=2019-08-30|archive-url=https://web.archive.org/web/20190830213436/http://isro.gov.in/update/28-sep-2018/three-years-of-astrosat|url-status=dead}}</ref>

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 [[Astronomy:Magellanic Clouds|Magellanic Clouds]]. This source is the first ULX pulsar discovered with the AstroSat mission and only the eight known ULX pulsar.<ref>
{{cite journal
| author1 = Chandra, A. D.|author2=Roy, J. |author3=Agrawal, P. C.|author4=Choudhury, M.
| title = Study of recent outburst in the Be/X-ray binary RX J0209.6−7427 with AstroSat: a new ultraluminous X-ray pulsar in the Magellanic Bridge?
| journal = Monthly Notices of the Royal Astronomical Society
| date = 2020
| volume = 495
| issue = 3
| pages = 2664–2672
| doi = 10.1093/mnras/staa1041
| bibcode =  2020MNRAS.495.2664C
|arxiv = 2004.04930|s2cid=215737137 }}</ref><ref>{{cite news |title=Ultra-bright X-ray source awakens near a galaxy not so far away |url=https://ras.ac.uk/news-and-press/research-highlights/ultra-bright-x-ray-source-awakens-near-galaxy-not-so-far-away |date=June 2020 |work=Royal Astronomical Society}}</ref><ref>{{cite news |title=Ultra-Bright Pulsar Awakens Next Door To The Milky Way After 26-Year Slumber |url=https://www.iflscience.com/space/ultrabright-pulsar-awakens-next-door-to-the-milky-way-after-26year-slumber/ |date= June 2020 |work=Alfredo Carpineti}}</ref>

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 [[Organization:Inter-University Centre for Astronomy and Astrophysics|Inter-University Centre for Astronomy and Astrophysics]], Pune.<ref>{{cite news | title=Global team of scientists discovers one of the earliest galaxies using India's AstroSat | url=https://indianexpress.com/article/technology/science/global-team-led-by-iucaa-scientists-marks-a-major-breakthrough-6568281/ |website=The Indian Express }}</ref><ref>{{cite journal|vauthors=Saha, K , Tandon, S N , Simmonds, C et al.|date=24 August 2020|title=AstroSat detection of Lyman continuum emission from a z = 1.42 galaxy.|url=https://www.nature.com/articles/s41550-020-1173-5%20#citeas|journal=Nature Astronomy|volume=4|issue=12 |page=1185|doi=10.1038/s41550-020-1173-5|arxiv=2008.11394|bibcode=2020NatAs...4.1185S|s2cid=221319445|access-date=6 November 2020}}</ref>

== In popular culture ==
In 2019 a documentary titled ''Indian Space Dreams'' on the developmental journey of Astrosat, and directed by Sue Sudbury, was released.<ref>{{Citation|title=Indian Space Dreams|url=http://www.imdb.com/title/tt11178478/|access-date=2020-01-27}}</ref>

==Gallery==
<gallery>
File:AstroSatPicN1 medium.jpg.webp|FUV Images of the [[Astronomy:NGC 1851|NGC-1851]] cluster
File:Apom nov18 medium.webp|[[Astronomy:Messier 74|Messier 74]] captured by astrosat
</gallery>

==See also==
*[[Astronomy:AstroSat-2|AstroSat-2]]
*[[Astronomy:Indian Astronomical Observatory|Indian Astronomical Observatory]]
*[[Astronomy:Indian Space Research Organisation|Indian Space Research Organisation]]
*[[Astronomy:List of space telescopes|List of space telescopes]]
*[[Astronomy:Ultraviolet astronomy|Ultraviolet astronomy]]
*[[Astronomy:X-ray astronomy|X-ray astronomy]]

== References ==
{{Reflist |2}}

==External links==
* [http://astrosat.iucaa.in/ ''Astrosat'']
* [http://www.isro.org/ ISRO]
* [https://link.springer.com/article/10.1007/s12036-017-9449-6 AstroSat: From Inception to Realization and Launch]

{{Indian space programme}}
{{Indian spacecraft}}
{{Space observatories}}
{{2015 in space}}

{{Use Indian English|date=January 2014}}

[[Category:Space telescopes]]
[[Category:Ultraviolet telescopes]]
[[Category:X-ray telescopes]]

{{Sourceattribution|AstroSat}}