Central Idea

India’s Giant Metrewave Radio Telescope (GMRT) is part of an international effort involving six large telescopes.
The telescopes have provided evidence confirming the presence of gravitational waves through pulsar observations.

Giant Metrewave Radio Telescope (GMRT)

The GMRT is an array of thirty fully steerable parabolic radio telescopes located near Narayangaon, Pune, in India.
It is renowned as the world’s largest and most sensitive radio telescope array operating at low frequencies.
It is operated by the National Centre for Radio Astrophysics (NCRA), a part of the Tata Institute of Fundamental Research, Mumbai.
It has made significant contributions to the field of astronomy since its construction under the guidance of Late Prof. Govind Swarup between 1984 and 1996.
The recent upgrade of the GMRT has further enhanced its capabilities, earning it the name “upgraded Giant Metrewave Radio Telescope” (uGMRT).

Location: The GMRT Observatory is situated approximately 80 km north of Pune, near Khodad, with the town of Narayangaon just 9 km away. The NCRA office is located within the Savitribai Phule Pune University campus.
Telescope Array: The GMRT consists of thirty fully steerable parabolic radio telescopes, each with a diameter of 45 meters.
Interferometry Array: The telescopes are configured in an interferometric array with baselines of up to 25 kilometres, allowing for precise and detailed observations.

Galaxy Formation and 21-cm Line Radiation: The GMRT was designed to search for highly redshifted 21-cm line radiation from primordial neutral hydrogen clouds, enabling the determination of the epoch of galaxy formation in the universe.
Diverse Astronomical Objectives: Astronomers from around the world utilize the GMRT for studying a wide range of celestial objects, including HII regions, galaxies, pulsars, and supernovae, as well as the Sun and solar winds.

Most Distant Galaxy: In August 2018, the GMRT discovered the most distant known galaxy, located 12 billion light-years away.
Ophiuchus Supercluster Explosion: In February 2020, the GMRT played a crucial role in observing the largest explosion ever recorded in the universe, the Ophiuchus Supercluster explosion.
Radio Signal from the Distant Universe: In January 2023, the GMRT detected a radio signal originating from 8.8 billion light-years away, specifically a fast radio burst (FRB) known as FRB 2023L.

Time Aberrations: The team observed time aberrations in the signals emitted by pulsars, indicating the possible presence of gravitational waves.
Galactic-Scale Gravitational Wave Detector: Scientists distributed ultra-stable pulsar clocks across the Milky Way to create a virtual detector sensitive to gravitational wave signals.
Arrival Time Variations: The arrival times of signals from pulsars were affected by the presence of gravitational waves, causing slight delays or advances.

Humming Signals: Nano-hertz signals caused by gravitational waves were detected, leading to the identification of their presence in the universe.
Opening a New Window: The team’s results represent a significant milestone in exploring the gravitational wave spectrum, providing new insights into astrophysics.
Sensitivity and Timeframe: Detecting these elusive nano-hertz gravitational waves requires sensitive telescopes like GMRT and long-term observations due to their slow variations.