IAS Gyan

Daily News Analysis


3rd June, 2022 Science and Technology

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  • India’s first liquid-mirror telescope has now entered the commissioning phase and will start scientific observations in October this year.


Design and collaboration

  • ILMT is built by astronomers from India, Belgium and Canada.
  • The telescope was designed and built at the Advanced Mechanical and Optical Systems Corporation and the Centre Spatial de Liege, Belgium.
  • The major instrumentation funding was jointly provided by Canada and Belgium while India will be responsible for the operations and upkeep of the telescope.


ILMT and its features


  • Established on the campus of the Devasthal Observatory of the Aryabhatta Research Institute of Observational Sciences (ARIES) in Nainital, the International Liquid Mirror Telescope (ILMT) is the only liquid-mirror telescope operational anywhere in the world.

Working principle

  • The novel instrument employs a 4-meter-diameter rotating mirror made up of a thin film of liquid mercury to collect and focus light.
  • The scientists spun a pool of mercury, which is a reflective liquid, so that the surface curved into a parabolic shape. It is ideal for focusing light.
  • A thin transparent film of mylar protects the mercury from wind.
  • The reflected light passes through a sophisticated multi-lens optical corrector that produces sharp images over a wide field of view. A large-format electronic camera located at the focus records the images.
  • The rotation of the earth causes the images to drift across the camera, but this motion is compensated electronically by the camera. This mode of operation increases observing efficiency and makes the telescope particularly sensitive to faint and diffuse objects.



  • The Indian Liquid Mirror Telescope (ILMT) will help in surveying the sky, making it possible to observe several galaxies and other astronomical sources.
  • It will observe asteroids, supernovae, space debris and all other celestial objects from an altitude of 2,450 metres in the Himalayas,
  • Unlike the conventional telescopes that can be steered to track specific stellar source objects, the ILMT will be stationary.
  • When the regular science operations begin, ILMT will produce about 10 GB of data / night, which will be quickly analyzed to reveal variable and transient stellar sources.
  • The ILMT will operate every night for five years and carry out daily imaging except between June and August monsoon months, a precaution to protect the instruments from humid conditions.
  • With such large voluminous data soon to be generated, the applications and algorithms using big data, Machine Learning (ML) and Artificial Intelligence (AI) will be implemented while classifying the celestial objects.


Devasthal Observatory

  • Devasthal is an observatory in the district of Nainital in Uttarakhand state of India.
  • The observatory is situated in the Kumaon Himalayan regionat an altitude of 2450 meters.
  • Devasthal is a 6-m Devasthal optical telescope (DOT) - India’s largest optical telescope.
  • Currently, a 130-cm optical telescope is working at the site. The sites are managed by the Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital.
  • ILMT will be the third telescope to be operating from Devasthal after the 3.6-metre Devasthal Optical Telescope (DOT) — the largest in India commissioned in 2016 — and the 1.3-metre Devasthal Fast Optical Telescope (DFOT) inaugurated in 2010.