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GMRT: India’s Largest Radio Telescope  


From UPSC perspective, the following things are important :

Prelims level: Giant Metrewave Radio Telescope (GMRT)

Mains level: Not Much


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 and Specifications

  • 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.

Science and 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.

Remarkable Discoveries

  • 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.

Recent Observations

  • 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.

Significance of the Findings

  • 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.

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