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What the world’s largest liquid mirror telescope means for astronomy

Updated: Dec 9, 2022

The International Liquid Mirror Telescope, located in Uttarakhand, India, high in the Himalayas, started making observations in August this year.

The telescope, commissioned at Devasthal, a hill in Uttarakhand, will help in surveying the sky making it possible to observe several galaxies and other astronomical sources just by staring at the strip of sky that passes overhead. It is the first liquid mirror telescope in the country and the largest in Asia.




Built by astronomers from India, Belgium and Canada, the novel instrument employs a 4-meter-diameter rotating mirror made up of a thin film of liquid mercury to collect and focus light. It is located at an altitude of 2450 metres at the Devasthal Observatory campus of Aryabhatta Research Institute of Observational Sciences (ARIES), an autonomous institute under the Department of Science and Technology (DST), Govt. of India in Nainital district, Uttarakhand.

Such telescopes have benefits over conventional ones. Most importantly, they are much cheaper to build. But although the idea of a liquid telescope has been around for centuries, creating a viable one has proven fiendishly tricky. The ILMT was in the works for more than a decade. This year, it opened its eye for the first time. It is the largest of its kind, and the first built to carry out astronomical observations.

The telescope scans the night sky in the hope of spotting new phenomena – when it isn’t raining, that is.


Observing the same patch of the sky also has its advantages, especially in detecting transient objects. Scientists can look for changes by subtracting images taken on different nights.


“ILMT will generate a huge 10–15 GB of data nightly. So, advanced computational tools, artificial intelligence, and machine learning will be implemented to classify space objects,” Kuntal adds.


When it does discover objects, the steerable 3.6-meter Devasthal Optical Telescope next door will be able to take a quick follow-up observation.