GMRT : A miracle producing marvels

Giant Microwave Radio Telescope, widely known as GMRT, has played a pivotal role in shaping Indian Astronomy. Commissioned in 1995, it was an engineering marvel built by Indian engineers and scientists. it is located in Narayangaon, Pune, GMRT is the largest meter telescope and one of the world’s most sensitive radio telescopes in operation. It is spread across an area of 25 kilometers, made up of 30 dishes, each weighing around 100 tons and having a diameter of 45 m. These dishes are built based on the idea of SMART (Stretched Mesh Attached to Rope Trusses), which allows them to move freely while being economically cheap and super efficient.

Giant Microwave Radio Telescope                                                                The SMART idea ( Swarup, 1990)

The idea of GMRT was first proposed by the Late Dr. Govind Swaroop, widely regarded as the father of radio astronomy in India. The objective of this project was to make a highly sensitive aperture synthesis radio telescope that would complement Arecibo and VLS radio telescopes. In its first proposal, Prof Swarup submitted the model with 34 parabolic cylinders, but considering the innovation in the parabolic model, which made it cost-effective, it was re-proposed in 1985 to replace the cylinder with 30 dishes enabling an effective area of 25,000 m2. Shaped in a ‘Y’ configuration, it has seven antennas as a cluster in the center spread across the region of 1km x 1km; the rest of the 18 antennas are laid in the three arms. The ‘Y’ array is advantageous in giving a good U-V converge at both high and low inclinations. Moreover, it provides an angular resolution of 2 arc seconds and 20 arc seconds at 1420 and 150 MHz.. 

 Location and map of GMRT

In many ways, GMRT has shaped Indian astronomy. Operated by the National Centre for Radio Astrophysics (NCRA), a Tata Institute of Fundamental Research (TIFR) division, it published its first paper in 1997 in an international journal. Since then, it has played a pivotal role in many discoveries. Be it the discovery of neutral hydrogen around other galaxies or supporting missions to mars, GMRT has always been a frontier. 

In addition to these contributions, the GMRT has also been used to study radio emissions from distant galaxies and quasars, which are incredibly luminous objects that are thought to be powered by supermassive black holes. This has allowed Indian astronomers to learn more about the evolution of galaxies and the process of galaxy formation. The oldest known fossil radio galaxy is the latest in this series of discoveries. The pair of gigantic lobes of the radio galaxy spanning 1.2 million light-years is located inside the galaxy cluster Abell 980 and was formed about 260 million years ago.  

Optical image of  galaxy parent to the radio lobes

Recently GMRT also became only the third institute in India to be awarded the IEEE milestone. To conclude, GMRT, in the truest sense, was a strenuous ambition in the 90s, which was made into a reality most elegantly by Indian scientists.

-Sanskar (MS21234)