Giant Metrewave Radio Telescope

The Giant Metrewave Radio Telescope (GMRT), located near Narayangaon, Pune in India, is an array of thirty fully steerable parabolic radio telescopes of 45 metre diameter, observing at metre wavelengths. It is the largest and most sensitive radio telescope array in the world at low frequencies.[1] 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 Late Prof. Govind Swarup during 1984 to 1996.[2] It is an interferometric array with baselines of up to 25 kilometres (16 mi).[3][4][5] It was recently upgraded with new receivers, after which it is also known as the upgraded Giant Metrewave Radio Telescope (uGMRT).[6]

Giant Metrewave Radio Telescope
Alternative namesGMRT
Location(s)Narayangaon, Pune district, Pune division, Maharashtra, India
Coordinates19°05′47″N 74°02′59″E
OrganizationNational Centre for Radio Astrophysics Edit this on Wikidata
Wavelength50, 1,500 MHz (6.00, 0.20 m)
First light1995 Edit this on Wikidata
Telescope styleradio interferometer Edit this on Wikidata
Number of telescopes30 Edit this on Wikidata
Diameter45 m (147 ft 8 in)
Collecting area47,713 m2 (513,580 sq ft)
Websitewww.gmrt.ncra.tifr.res.in
Giant Metrewave Radio Telescope is located in India
Giant Metrewave Radio Telescope
Location of Giant Metrewave Radio Telescope
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Location

The Giant Metrewave Radio Telescope (GMRT) Observatory is located about 80 km north of Pune at Khodad. A nearby town is Narayangaon which is around 9 km from the 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 redshifted 21-cm line radiation from primordial neutral hydrogen clouds in order to determine the epoch of galaxy formation in the universe.[7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]

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, microquasars or binary stars with a compact object (neutron star or black hole) as companion, pulsars, supernovae, supernovae remnants (SNR) HII regions, galaxies, quasars, radio galaxies, clusters of galaxies, cluster radio relics and halos, high-z galaxies, solar winds, 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 etc. .[3][6]

GMRT has produced an all sky survey named TIFR GMRT Sky Survey (TGSS). Nearly 90% of the sky has been imaged at the frequency of 150 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.[31] General public and citizen scientists can see 150 MHz image of any, supernova remnant, spiral galaxy or radio galaxy with its name or position at the 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.[32]

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.[33][34]

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.[35]

In January 2023, the telescope picked up a radio signal (21 cm line emission from neutral atomic hydrogen gas) which originated from 8.8 billion light years away. [36]

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).

See also

References
  1. "The Giant Metrewave Radio Telescope". NCRA website.
  2. Prof. Govind Swarup: The Father of Radio Astronomy in India
  3. Ananthakrishnan, S. (1995). "The giant meterwave radio telescope" (PDF). Journal of Astrophysics and Astronomy. 16: 433. Retrieved 27 June 2015.
  4. Ishwara-Chandra, C H; Rao, A Pramesh; Pandey, Mamta; Manchanda, R K; Durouchoux, Philippe (2005). "Low Frequency Radio Observations of GRS1915+105 with GMRT". Chinese Journal of Astronomy and Astrophysics. 5 (S1): 87–92. arXiv:astro-ph/0512061. Bibcode:2005ChJAS...5...87I. doi:10.1088/1009-9271/5/S1/87.
  5. 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.
  6. Gupta, Y.; Ajithkumar, B.; Kale, H. S.; Nayak, S.; Sabhapathy, S.; Sureshkumar, S.; Swami, R. V.; Chengalur, J. N.; Ghosh, S. K.; Ishwara-Chandra, C. H.; Joshi, B. C.; Kanekar, N.; Lal, D. V.; Roy, S. (25 August 2017). "The Upgraded GMRT:Opening New Windows on the Radio Universe" (PDF). Current Science. 113 (04): 707. doi:10.18520/cs/v113/i04/707-714. ISSN 0011-3891.
  7. Kapahi, V. K.; Ananthakrishnan, S. (1995). "Astronomy with the giant metrewave radio telescope (GMRT)" (PDF). Bulletin of the Astronomical Society of India. 23: 267. Bibcode:1995BASI...23..265K. Retrieved 27 June 2015.
  8. Bharadwaj, Somnath; Nath, Biman B.; Sethi, Shiv K. (1 March 2001). "Using HI to probe large scale structures at z~3". Journal of Astrophysics and Astronomy. 22 (1): 21–34. arXiv:astro-ph/0003200. Bibcode:2001JApA...22...21B. doi:10.1007/BF02933588. ISSN 0250-6335. S2CID 14407741.
  9. Bharadwaj, S.; Nath, B. B.; Sethi, S. K. (2002). "Probing Large Scale Structures in HI with GMRT". The Universe at Low Radio Frequencies. 199: 108–109. Bibcode:2002IAUS..199..108B. doi:10.1017/s0074180900168640.
  10. Bharadwaj, Somnath; Sethi, Shiv K. (1 December 2001). "HI fluctuations at large redshifts: I-visibility correlation". Journal of Astrophysics and Astronomy. 22 (4): 293–307. arXiv:astro-ph/0203269. Bibcode:2001JApA...22..293B. doi:10.1007/BF02702273. ISSN 0973-7758. S2CID 14605700.
  11. Bharadwaj, Somnath; Pandey, Sanjay K. (1 March 2003). "HI Fluctuations at Large Redshifts: II - the Signal Expected for the GMRT". Journal of Astrophysics and Astronomy. 24 (1–2): 23–35. arXiv:astro-ph/0307303. Bibcode:2003JApA...24...23B. doi:10.1007/BF03012189. ISSN 0250-6335. S2CID 18496656.
  12. Bharadwaj, Somnath; Srikant, P. S. (1 March 2004). "HI Fluctuations at Large Redshifts: III - Simulating the Signal Expected at GMRT". Journal of Astrophysics and Astronomy. 25 (1–2): 67–80. arXiv:astro-ph/0402262. Bibcode:2004JApA...25...67B. doi:10.1007/BF02702289. ISSN 0250-6335. S2CID 8964798.
  13. Pandey, Sanjay K.; Bharadwaj, Somnath; Saiyad Ali, S. K. (11 February 2006). "Probing the bispectrum at high redshifts using 21-cm H i observations". Monthly Notices of the Royal Astronomical Society. 366 (1): 213–218. arXiv:astro-ph/0510118. doi:10.1111/j.1365-2966.2005.09847.x. ISSN 0035-8711. S2CID 7600009.
  14. Choudhury, T. Roy; Bharadwaj, Somnath; Datta, Kanan K. (1 December 2007). "Detecting ionized bubbles in redshifted 21-cm maps". Monthly Notices of the Royal Astronomical Society. 382 (2): 809–818. arXiv:astro-ph/0703677. Bibcode:2007MNRAS.382..809D. doi:10.1111/j.1365-2966.2007.12421.x. ISSN 0035-8711.
  15. Chengalur, Jayaram N.; Bharadwaj, Somnath; Ali, Sk Saiyad (21 April 2008). "Foregrounds for redshifted 21-cm studies of reionization: Giant Meter Wave Radio Telescope 153-MHz observations". Monthly Notices of the Royal Astronomical Society. 385 (4): 2166–2174. arXiv:0801.2424. Bibcode:2008MNRAS.385.2166A. doi:10.1111/j.1365-2966.2008.12984.x. ISSN 0035-8711. S2CID 13541850.
  16. Choudhury, T. Roy; Bharadwaj, Somnath; Majumdar, Suman; Datta, Kanan K. (21 December 2008). "Simulating the impact of H i fluctuations on matched filter search for ionized bubbles in redshifted 21-cm maps". Monthly Notices of the Royal Astronomical Society. 391 (4): 1900–1912. arXiv:0805.1734. Bibcode:2008MNRAS.391.1900D. doi:10.1111/j.1365-2966.2008.14008.x. ISSN 0035-8711. S2CID 15646124.
  17. Choudhury, T. Roy; Bharadwaj, Somnath; Datta, Kanan K. (1 October 2009). "The optimal redshift for detecting ionized bubbles in Hi 21-cm maps". Monthly Notices of the Royal Astronomical Society: Letters. 399 (1): L132–L136. arXiv:0906.0360. Bibcode:2009MNRAS.399L.132D. doi:10.1111/j.1745-3933.2009.00739.x. ISSN 1745-3925. S2CID 8941846.
  18. Choudhury, T. Roy; Datta, Kanan K.; Bharadwaj, Somnath; Majumdar, Suman (11 May 2011). "The impact of anisotropy from finite light traveltime on detecting ionized bubbles in redshifted 21-cm maps". Monthly Notices of the Royal Astronomical Society. 413 (2): 1409–1418. arXiv:1006.0430. Bibcode:2011MNRAS.413.1409M. doi:10.1111/j.1365-2966.2011.18223.x. ISSN 0035-8711. S2CID 8869385.
  19. Ghosh, Abhik; Bharadwaj, Somnath; Ali, Sk. Saiyad; Chengalur, Jayaram N. (1 March 2011). "GMRT observation towards detecting the post-reionization 21-cm signal". Monthly Notices of the Royal Astronomical Society. 411 (4): 2426–2438. arXiv:1010.4489. Bibcode:2011MNRAS.411.2426G. doi:10.1111/j.1365-2966.2010.17853.x. ISSN 0035-8711. S2CID 119230101.
  20. Ghosh, Abhik; Bharadwaj, Somnath; Ali, Sk. Saiyad; Chengalur, Jayaram N. (1 December 2011). "Improved foreground removal in GMRT 610 MHz observations towards redshifted 21-cm tomography". Monthly Notices of the Royal Astronomical Society. 418 (4): 2584–2589. arXiv:1108.3707. Bibcode:2011MNRAS.418.2584G. doi:10.1111/j.1365-2966.2011.19649.x. ISSN 0035-8711. S2CID 118437718.
  21. Choudhury, T. Roy; Bharadwaj, Somnath; Majumdar, Suman (11 November 2012). "Constraining quasar and intergalactic medium properties through bubble detection in redshifted 21-cm maps". Monthly Notices of the Royal Astronomical Society. 426 (4): 3178–3194. arXiv:1111.6354. Bibcode:2012MNRAS.426.3178M. doi:10.1111/j.1365-2966.2012.21914.x. ISSN 0035-8711. S2CID 118436604.
  22. Chengalur, Jayaram N.; Ali, Sk Saiyad; Bharadwaj, Somnath; Prasad, Jayanti; Ghosh, Abhik (11 November 2012). "Characterizing foreground for redshifted 21 cm radiation: 150 MHz Giant Metrewave Radio Telescope observations". Monthly Notices of the Royal Astronomical Society. 426 (4): 3295–3314. arXiv:1208.1617. Bibcode:2012MNRAS.426.3295G. doi:10.1111/j.1365-2966.2012.21889.x. ISSN 0035-8711. S2CID 54662482.
  23. Ghosh, A.; Prasad, J.; Bharadwaj, S.; Ali, Sk. S.; Chengalur, J. N. (1 April 2013). "VizieR Online Data Catalog: Complete 150MHz GMRT source catalogue (Ghosh+, 2012)". VizieR On-line Data Catalog. 742. Bibcode:2013yCat..74263295G.
  24. Ali, Sk Saiyad; Ghosh, Abhik; Bharadwaj, Somnath; Choudhuri, Samir (21 December 2014). "Visibility-based angular power spectrum estimation in low-frequency radio interferometric observations". Monthly Notices of the Royal Astronomical Society. 445 (4): 4351–4365. arXiv:1409.7789. Bibcode:2014MNRAS.445.4351C. doi:10.1093/mnras/stu2027. ISSN 0035-8711.
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  26. Ghosh, Abhik; Roy, Nirupam; Ali, Sk Saiyad; Chatterjee, Suman; Bharadwaj, Somnath; Choudhuri, Samir (21 December 2016). "The visibility-based tapered gridded estimator (TGE) for the redshifted 21-cm power spectrum". Monthly Notices of the Royal Astronomical Society. 463 (4): 4093–4107. arXiv:1609.01732. Bibcode:2016MNRAS.463.4093C. doi:10.1093/mnras/stw2254. ISSN 0035-8711.
  27. Ali, Sk. Saiyad; Bharadwaj, Somnath; Choudhuri, Samir; Ghosh, Abhik; Roy, Nirupam (28 November 2016). "Prospects of Measuring the Angular Power Spectrum of the Diffuse Galactic Synchrotron Emission with SKA1 Low" (PDF). Journal of Astrophysics and Astronomy. 37 (4): 35. arXiv:1610.08184. Bibcode:2016JApA...37...35A. doi:10.1007/s12036-016-9413-x. ISSN 0973-7758. S2CID 55989492.
  28. Ghosh, Abhik; Intema, Huib T.; Roy, Nirupam; Ali, Sk Saiyad; Bharadwaj, Somnath; Choudhuri, Samir (1 September 2017). "The angular power spectrum measurement of the Galactic synchrotron emission in two fields of the TGSS survey". Monthly Notices of the Royal Astronomical Society: Letters. 470 (1): L11–L15. arXiv:1704.08642. Bibcode:2017MNRAS.470L..11C. doi:10.1093/mnrasl/slx066. ISSN 1745-3925.
  29. Chatterjee, Suman; Bharadwaj, Somnath (1 February 2019). "On the prospects of measuring the cosmic dawn 21-cm power spectrum using the upgraded Giant Metrewave Radio Telescope (uGMRT)". Monthly Notices of the Royal Astronomical Society. 483 (2): 2269–2274. arXiv:1804.00515. Bibcode:2019MNRAS.483.2269C. doi:10.1093/mnras/sty3242. ISSN 0035-8711.
  30. Dutta, Prasun; Choudhuri, Samir; Pal, Srijita; Bharadwaj, Somnath (11 March 2019). "A Tapered Gridded Estimator (TGE) for the multifrequency angular power spectrum (MAPS) and the cosmological H i 21-cm power spectrum". Monthly Notices of the Royal Astronomical Society. 483 (4): 5694–5700. arXiv:1812.08801. Bibcode:2019MNRAS.483.5694B. doi:10.1093/mnras/sty3501. ISSN 0035-8711.
  31. Intema, H. T.; Jagannathan, P.; Mooley, K. P.; Frail, D. A. (February 2017). "The GMRT 150 MHz all-sky radio survey: First alternative data release TGSS ADR1". Astronomy & Astrophysics. 598: A78. doi:10.1051/0004-6361/201628536. ISSN 0004-6361.
  32. Kembhavi, Ajit K.; Chengalur, Jayaram N. (19 April 2023). "Govind Swarup. 23 March 1929—7 September 2020". Biographical Memoirs of Fellows of the Royal Society. doi:10.1098/rsbm.2022.0049. ISSN 0080-4606.
  33. Netherlands Research School for Astronomy (8 August 2018). "Astronomers report the most distant radio galaxy ever discovered". Phys.org. Science X Network. doi:10.1093/mnras/sty1996. Retrieved 23 July 2023.
  34. "Telescope In Pune Discovers Most Distant Radio Galaxy Ever Found". NDTV.com. Retrieved 13 June 2019.
  35. "Astronomers detect biggest explosion in the history of the Universe". ScienceDaily. Retrieved 27 February 2020.
  36. https://www.indiatoday.in/science/story/indian-astronomer-captures-radio-signal-that-originated-8-billion-years-ago-2324134-2023-01-20. {{cite web}}: Missing or empty |title= (help)
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