IIA Bengaluru, IIT Bombay Extend Collaboration On GROWTH-India Robotic Telescope In Ladakh

Housed within the Indian Astronomical Observatory (IAO) at Hanle, Ladakh, is an optical telescope dedicated to ‘time-domain astronomy’ — the observation of explosive transients and variable sources in the universe, which are essentially short-lived cosmic events.

Developed jointly by the Indian Institute of Astrophysics (IIA), Bengaluru, and the Indian Institute of Technology Bombay (IIT-B), Mumbai, the GROWTH-India Telescope has been used since 2018 to spot electromagnetic counterparts of gravitational wave sources, observe the death of stars, and keep a watch on asteroids that fly close to Earth.

Now, after over two years of successful operation, the high-altitude telescope has received a service extension. On 30 August 2021, project partners IIA Bengaluru and IIT-B signed an agreement to continue collaborating on the robotic optical telescope for five more years.

“The motivation was to ensure continuation of the GROWTH-India collaboration and continued operations of the GROWTH-India telescope with the involvement of IITB,” says Professor G C Anupama of IIA Bengaluru, who is one of two principal investigators for the telescope and the scientist in charge of the IAO facility in Ladakh.

“Another important aspect for pursuing the extension,” she adds, “is to enable undergraduate students at IIT-B to learn observation astronomy through the actual use of a telescope”.

The GROWTH-India telescope (GIT) has a 0.7 x 0.7 degrees field of view and a pixel scale of 0.7 arcseconds per pixel. It was set up to be part of the international GROWTH network: a 'Global Relay of Observatories Watching Transients Happen'.

The global GROWTH project is a collaboration between acclaimed institutions such as California Institute of Technology (United States), Los Alamos National Laboratory (United States), University of Maryland (United States), Tokyo Institute of Technology (Japan), Weizmann Institute of Science (Israel), and Humboldt University (Germany), in addition to India’s IIA and IIT-B.

The Indian wing of the project was supported by the Indo-US Science and Technology Forum and the Science and Engineering Research Board, Department of Science and Technology (Government of India). The operations of the telescope are partially supported by contributions from the 1994 batch alumni of IIT-B.

The GIT is India’s first fully robotic optical telescope. “The scripts for the operations of the telescope have been developed by the GROWTH-India IIT-B team. The telescope runs on a scheduler with minimal support from the IAO observing staff at the start of the observations,” Professor Anupama says.

Through instructions from Mumbai or Bengaluru, scientists remotely point the telescope in the desired direction and begin collecting data from a distant cosmic object of interest. The machine-based operation facilitates quick observation so that temporal cosmic events can be captured before they disappear into the darkness of space.

The GIT saw the first light — which is when it made the first observation of the skies — in the second week of June 2018. Since then, it has made many key observations.

“During the O3 run of LIGO, GIT was used for wide field search of GW events that were suspected to have a neutron star. Six such events were followed up. Although no optical counterpart was detected, the observations established the efficiency of the GIT for such studies in the future LIGO runs,” Professor Anupama says.

“O3” refers to the third observing run of the Laser Interferometer Gravitational-Wave Observatory, abbreviated as LIGO, and “GW” is short for gravitational wave.

The job of the LIGO detector is to detect gravitational waves emanating from the cataclysmic collision of enigmatic distant objects like black holes and neutron stars.

One of the goals of the GIT is to quickly track the source of a detected gravitational wave in the electromagnetic spectrum.

The GIT also picks up on gamma-ray bursts — fiercely bright glimpses of either the death of stars or collisions between black holes or neutron stars or a combination of the two.

“The optical afterglows of several gamma-ray burst sources and several young supernovae have been monitored with good cadence,” Professor Anupama says, adding that the data gathered is being used by PhD students for scientific research.

For Professor Anupama, the most exciting aspect of GIT observations has been the discovery of asteroids by students of IIT-B.

In August last year, undergraduate and graduate students Kritti Sharma, Kunal Deshmukh, and Harsh Kumar discovered the closest-known asteroid to fly past the Earth without impacting it using data from the Zwicky Transient Facility (ZTF).

The students worked on the GROWTH-India project with the aim to search, confirm, and follow-up on near-earth objects like asteroids. They collaborated with the ZTF.

Sharma, Deshmukh, and Kumar discovered 43 asteroids between them over a span of one and a half years, as of February 2021. They received a special commendation and silver medals under the "ASI New Discovery Award" for 2021 owing to their discovery and study of asteroids.

The extension for the GIT project will thankfully enable more undergraduate students to pursue observational astronomy through the use of a telescope.

Additionally, the GIT will be used for educational and outreach purposes.

This is not all. Professor Anupama says, “A fraction of the GIT time will continue to be made available to scientists outside of the GROWTH-India collaboration for variability studies, as the GIT is an extremely efficient telescope for observations of variability of astronomical sources.”

The chiefs of both IIA Bengaluru and IIT Bombay expressed great enthusiasm about the extension of the GROWTH-India collaboration after signing the memorandum of understanding.

“IIT Bombay aims to be a leader in astronomical research and this prestigious partnership with IIA brings us one step closer to our mission,” IIT-B director, Professor Subhasis Chaudhuri said in a statement.

“The wealth of expertise and experience of the IIA team in running telescope facilities in one of the best sites in the world combined with the young and enthusiastic team of IIT Bombay is a great collaboration that has already produced fascinating results in the last three years,” IIA director, Professor Annapurni Subramaniam was quoted as saying in the statement.

The GROWTH-India telescope sits alongside the Himalayan Chandra Telescope, the high-altitude gamma-ray array telescope (HAGAR), and the imaging Cherenkov telescope (MACE) at the IAO facility in Ladakh.

At 4,500 metres above mean sea level, the facility is one of the highest observatory sites in the world and India’s northernmost astronomy outpost.

Recently, the chief engineer of the observatory, Dorje Angchuk, was inducted to the International Astronomical Union (IAU) as an honorary member.