Our universe is expanding. Recent discoveries have shown that it is accelerating too. Scientists world over have been trying to understand why this is happening. And radio astronomy or the radio telescopes play a vital role in the entire understanding of the universe after the Big Bang.
The Giant Meterwave Radio Telescope (GMRT) is an important player in unraveling the mysteries of the universe. The major international facility to work in low-frequency of 150 mhz to 1.5 ghz consists of 30 parabolic radio telescopes with a diameter of 45 metre observing metre frequency. Located some 80 kms from Pune, it is open to public only on National Science Day (February 28).
From 1944 till 1960, Tata Institute of Fundamental Research (TIFR) used to carry out research in fundamental science. Its founding director Homi Bhabha wanted to introduce radio astronomy in the country. He formed a group and brought in Australian antennas. The Kalyan telescope was the first project. After successful completion of this project, the Ooty cylindrical telescope was shaped under Prof Govind Swarup who is renowned for founding the GMRT also.
Later in the year 1984, the proposal for GMRT was submitted to the government. Total 30 antennas were erected in Y-shaped formation. “The basic feature of radio astronomy is to have very large area to collect signals and powerful receivers to receive signals,” said Science Outreach Person JK Solanki.
Solanki further added, “Making one 25 km antenna was not physically and financially possible. Therefore, 30 small antennas were made and as per the physics interferometer put into shaped in Y alphabetical letter in a linear position directed towards one single object. The signals received from this were correlated, processed and converted into image using astronomical software.”
“All antennas are identical, mounted on a 12-metre concrete tower, with total height of 40 m from the surface, with diameter of 45 metres and weight 110 tonnes. A thin mesh has been installed which works like a mirror reflection of the waves. The top receivers and wires convert signals into electronics and send it to the control room, where the scientists observe them,” he added.
Director of National Centre for Radio Astrophysics (NCRA) Yashwant Gupta said, “Recently, GMRT was upgraded to be in line with the newer technology and concepts. We refurbished the entire receiving system of electronics and corresponding hardware for processing the data and the corresponding software to handle large amounts of data to be able to cover the frequency length continuously without any gap.”
Upgraded GMRT and SKA
“Recently, there was an upgrade that will improve the antennae’s sensitivity by a factor of up to three. The 1980’s target spectrum was 32 MHz. It is working fine, but we can do better with newer technologies.” Gupta said. “GMRT is a part of Square Kilometre Array (SKA) project which aims at building the world’s largest radio telescope, with eventually over a square kilometre (one million square metres) of collecting area.
“The SKA will eventually use thousands of dishes and up to a million low-frequency antennae that will enable astronomers to monitor the sky in unprecedented detail and survey sky much faster than any system currently in existence,” Gupta added.
Giving the relevance of GMRT in SKA, Gupta said there are two major points.
1. SKA is based in southern hemisphere, thus southern hemisphere is unable to see the northern skies but here the GMRT will be able to see it, besides it is accessible too.
2. SKA is a heavily subscribed object so researchers will turn to GMRT for various other facilities since it was properly maintained.
