View source for Giant Metrewave Radio Telescope

{{Short description|Radio telescope center}}
{{Use dmy dates|date=March 2019}}
{{Use Indian English|date=August 2015}}
{{Infobox Telescope}}
The '''Giant Metrewave Radio Telescope''' ('''GMRT'''), located near [[Narayangaon]], [[Pune]] in India, is an array of thirty fully steerable parabolic [[radio telescope]]s of 45 metre diameter, observing at metre [[wavelength]]s. It is the largest and most sensitive radio telescope array in the world at low frequencies.<ref>{{cite web |title=The Giant Metrewave Radio Telescope |url=http://www.ncra.tifr.res.in/ncra/research/research-at-ncra-tifr/research-areas/GMRT/GMRT |website=NCRA website |language=en-us}}</ref> It is operated by the National Centre for Radio Astrophysics (NCRA), a part of the [[Tata Institute of Fundamental Research]], [[Mumbai]]. It was conceived and built under the direction of [[Govind Swarup]] during 1984 to 1996.<ref>[http://www.gmrt.ncra.tifr.res.in/news/gs.html Prof. Govind Swarup: The Father of Radio Astronomy in India]</ref> It is an [[Interferometry|interferometric]] array with baselines of up to {{convert|25|km|mi}}.<ref name=Ananthakrishnan1995>{{cite journal|last1=Ananthakrishnan|first1=S.|title=The giant meterwave radio telescope.|journal=Journal of Astrophysics and Astronomy|date=1995|volume=16|page=433|url=http://repository.ias.ac.in/605/1/347.pdf|access-date=27 June 2015}}</ref><ref>{{cite journal |doi=10.1088/1009-9271/5/S1/87 |last1=Ishwara-Chandra |first1=C H |last2=Rao |first2=A Pramesh |last3=Pandey |date=2005 |first3=Mamta |last4=Manchanda |first4=R K |last5=Durouchoux |first5=Philippe |title=Low Frequency Radio Observations of GRS1915+105 with GMRT|journal= Chinese Journal of Astronomy and Astrophysics|volume= 5 |issue=S1|pages= 87–92|bibcode= 2005ChJAS...5...87I|arxiv = astro-ph/0512061 }}</ref><ref>Swarup, G., Ananthkrishnan, S., Kapahi, V.K., Rao, A.P., Subrahamanya, C.R., and Kulkarni, V.K. (1991) "The Giant Metrewave Radio Telescope", Current Science, vol. 60, pages 90-105.</ref> It was recently upgraded with new receivers, after which it is also known as the '''upgraded Giant Metrewave Radio Telescope''' ('''uGMRT''').<ref name=":0">{{Cite journal |last1=Gupta |first1=Y. |last2=Ajithkumar |first2=B. |last3=Kale |first3=H. S. |last4=Nayak |first4=S. |last5=Sabhapathy |first5=S. |last6=Sureshkumar |first6=S. |last7=Swami |first7=R. V. |last8=Chengalur |first8=J. N. |last9=Ghosh |first9=S. K. |last10=Ishwara-Chandra |first10=C. H. |last11=Joshi |first11=B. C. |last12=Kanekar |first12=N. |last13=Lal |first13=D. V. |last14=Roy |first14=S. |date=2017-08-25 |title=The Upgraded GMRT:Opening New Windows on the Radio Universe |url=http://www.currentscience.ac.in/Volumes/113/04/0707.pdf |journal=Current Science |volume=113 |issue=4 |pages=707 |doi=10.18520/cs/v113/i04/707-714 |bibcode=2017CSci..113..707G |issn=0011-3891}}</ref>

==Location==
The Giant Metrewave Radio Telescope (GMRT) Observatory is located about 80&nbsp;km north of [[Pune]] at [[Khodad]]. A nearby town is [[Narayangaon]] which is around 9&nbsp;km from the [[Radio telescope|telescope]] site. The office of [[National Centre for Radio Astrophysics]] (NCRA) is located in the [[Savitribai Phule Pune University]] campus.

==Science and observations==
One of the aims for the telescope during its development was to search for the highly [[redshift]]ed 21-cm line radiation from primordial neutral hydrogen clouds in order to determine the epoch of galaxy formation in the [[universe]].<ref>{{Cite journal|last1=Chatterjee|first1=Suman|last2=Bharadwaj|first2=Somnath|date=2019-02-01|title=On the prospects of measuring the cosmic dawn 21-cm power spectrum using the upgraded Giant Metrewave Radio Telescope (uGMRT)|journal=Monthly Notices of the Royal Astronomical Society|volume=483|issue=2|pages=2269–2274|doi=10.1093/mnras/sty3242|doi-access=free |issn=0035-8711|bibcode=2019MNRAS.483.2269C|arxiv=1804.00515}}</ref>

Astronomers from all over the world regularly use this telescope to observe many different astronomical objects such as the [[Sun]], Jupiter, exoplanets, magnetically active stars, [[microquasar]]s or binary stars with a compact object (neutron star or black hole) as companion, [[pulsar]]s, [[supernova]]e, [[Supernova remnant|supernovae remnants]] (SNR) [[HII regions]], [[galaxies]], [[quasar]]s, [[Radio galaxy|radio galaxies]], [[clusters of galaxies]], cluster radio relics and halos,  high-z galaxies,  [[solar wind]]s, Inter-galactic HI absorption lines, diffuse radio emission from filaments of galaxies, possible signs of [[time-variation of fundamental constants]], variation of gas content with cosmic epoch, [[Epoch of Reionisation|epoch of reionisation]] etc. .<ref name=Ananthakrishnan1995 /><ref name=":0" />

GMRT has produced an all sky survey named [[Tata Institute of Fundamental Research|TIFR]] GMRT Sky Survey (TGSS). Nearly 90% of the sky has been imaged at the frequency of 150&nbsp;MHz (wavelength 2m), with an angular resolution of 25 arc second and rms noise of 5 mili Jansky per beam. Source Catalogue and FITS image files for the scientific community are freely available.<ref>{{Cite journal |last1=Intema |first1=H. T. |last2=Jagannathan |first2=P. |last3=Mooley |first3=K. P. |last4=Frail |first4=D. A. |date=February 2017 |title=The GMRT 150 MHz all-sky radio survey: First alternative data release TGSS ADR1 |url=http://www.aanda.org/10.1051/0004-6361/201628536 |journal=Astronomy & Astrophysics |volume=598 |pages=A78 |doi=10.1051/0004-6361/201628536 |arxiv=1603.04368 |bibcode=2017A&A...598A..78I |s2cid=15961445 |issn=0004-6361}}</ref> General public and citizen scientists can see 150&nbsp;MHz image of any, supernova remnant, spiral galaxy or radio galaxy with its name or position at the [https://www.radathomeindia.org/rgbmaker RAD@home RGB-maker web-tool]. Power and versatility of the GMRT has led to a renaissance in the field of low frequency radio astronomy.<ref>{{Cite journal |last1=Kembhavi |first1=Ajit K. |last2=Chengalur |first2=Jayaram N. |date=2023-04-19 |title=Govind Swarup. 23 March 1929—7 September 2020 |journal=Biographical Memoirs of Fellows of the Royal Society |volume=75 |pages=455–478 |language=en |doi=10.1098/rsbm.2022.0049 |issn=0080-4606|doi-access=free }}</ref>

From this, TGSS survey, data, in August 2018, the most distant known  radio  galaxy : TGSS J1530+1049, located at a distance of 12 billion light years, was discovered by GMRT.<ref name="NRSA 5.72">{{cite journal |author1=Netherlands Research School for Astronomy |title=Astronomers report the most distant radio galaxy ever discovered |url=https://phys.org/news/2018-08-astronomers-distant-radio-galaxy.html |website=Phys.org |publisher=Science X Network |access-date=23 July 2023 |doi=10.1093/mnras/sty1996 |date=8 Aug 2018|doi-access=free |hdl=1887/71688 |hdl-access=free |arxiv=1806.01191 }}</ref><ref>{{Cite web|url=https://www.ndtv.com/science/at-12-billion-light-years-telescope-in-pune-discovers-most-distant-radio-galaxy-ever-found-1897771|title=Telescope In Pune Discovers Most Distant Radio Galaxy Ever Found|website=NDTV.com|access-date=2019-06-13}}</ref>

In February 2020, it helped in the observation of evidence of the largest known explosion in the history of the universe, the [[Ophiuchus Supercluster explosion]].<ref>{{Cite web|url=https://www.sciencedaily.com/releases/2020/02/200227114459.htm|title=Astronomers detect biggest explosion in the history of the Universe|website=ScienceDaily|language=en|access-date=2020-02-27}}</ref>

In January 2023, the telescope picked up a radio signal (21&nbsp;cm line emission from neutral atomic hydrogen gas) which originated from 8.8 billion light years away.
<ref>{{Cite web|url=https://www.indiatoday.in/science/story/indian-astronomer-captures-radio-signal-that-originated-8-billion-years-ago-2324134-2023-01-20 |title=Indian astronomer captures radio signal that originated 8 billion years ago |date=20 January 2023 }}</ref>

==Activities==
Each year on [[National Science Day]] the observatory invites the public and pupils from schools and colleges in the surrounding area to visit the site where they can listen to explanations of radio astronomy, receiver technology and astronomy from the engineers and astronomers who work there. Nearby schools/colleges are also invited to put their individual science experiments in exhibition and the best one in each level (primary, secondary school and Jr. college) are awarded.

Visitors are allowed into GMRT only on Fridays in two sessions - Morning (1100 hrs - 1300 hrs) and Evening (1500 hrs to 1700 hrs).

==Gallery==
<gallery mode="packed" heights="134">
File:Remote closeup view of one GMRT antenna through the fields.jpg|GMRT antenna 
File:Plaque of GMRT at the entrance gate.jpg| Plaque of GMRT at the entrance gate
File:Main administrative building of GMRT in the campus.jpg|Main administrative building of GMRT in the campus
File:Backside view of GMRT C-3 antenna from the right.jpg|Backside view of GMRT C-3 antenna from the right
File:New building of GMRT under construction in the campus.jpg|New building of GMRT under construction in the campus
</gallery>

==See also==
* [[List of radio telescopes]]

==References==
{{Reflist}}

==External links==
{{commons category|GMRT}}
* [http://www.gmrt.ncra.tifr.res.in/ GMRT Homepage]
* [http://www.gmrt.ncra.tifr.res.in/gmrt_hpage/Images/Diagrams/yarray.gif Y-shaped array]
* [https://web.archive.org/web/20090807085328/http://ncra.tifr.res.in/~res/visittogmrt/VISIT_GMRT.htm Visit GMRT]
* [http://www.10ccscienceclub.com/our-clubs-community/80-the-original-one/83-gmrt-visit/ GMRT Visit] {{Webarchive|url=https://web.archive.org/web/20150225110931/http://www.10ccscienceclub.com/our-clubs-community/80-the-original-one/83-gmrt-visit/ |date=25 February 2015 }}

{{radio-astronomy}}
{{Telescopes and Observatories in India}}
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[[Category:Radio telescopes]]
[[Category:Interferometric telescopes]]
[[Category:Astronomical observatories in India]]
[[Category:Tata Institute of Fundamental Research]]
[[Category:1995 establishments in Maharashtra]]
[[Category:Pune district]]
[[Category:Research institutes in Maharashtra]]