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India’s First & Asia’s Largest International Liquid-Mirror Telescope Commissioned at Devasthal Hill, Uttarakhand

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Asia's Largest Liquid Mirror Telescope Commissioned At Uttarakhand's Devasthal

India has commissioned its first and Asia’s largest International Liquid-Mirror Telescope (ILMT) atop Devasthal hill, in the Indian Himalayas, in Uttarakhand. It became the world’s first liquid-mirror telescope to be commissioned for astronomy.

It is situated 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), Ministry of Science and Technology (MoST), in Nainital district, Uttarakhand.


  • The liquid-mirror telescope will monitor the sky for transient or variable objects like supernovae, gravitational lenses, space debris, and asteroids.
  • The telescope will aid in the surveying of the sky, as well as allowing the observation of numerous galaxies and other astronomical sources by glancing at the strip of sky that passes overhead.

Key Features of The International Liquid-Mirror Telescope (ILMT)

i. The International Liquid Mirror Telescope (ILMT) is a 4-meter (m) class telescope project in which multiple institutions from several countries are actively involved, including Belgium, Canada, India, and Poland.

  • The telescope was designed and built by the Advanced Mechanical and Optical Systems (AMOS) Corporation and the Centre Spatial de Liège in Belgium.

ii.The ILMT employs Liquid Mirror technology, which consists of three key components:

  • The primary mirror of the telescope, a rotating container with a highly-reflective liquid in it (essentially mercury);
  • An ​air ​bearing, which ​supports the ​​liquid ​mirror ​; and
  • ​A ​drive ​system.

iii. Mercury, a reflective liquid, is used on the surface of the telescope, so that it can be curved into a parabolic shape, which is ideal for focusing light. The mercury is protected from the wind by a thin mylar film.

  • The reflected light is processed by a multi-lens optical corrector, which creates sharp images across a wide field of view. The images are captured using a large-format electronic camera mounted at the focus.
  • The images drift across the camera due to the earth’s rotation, but the motion will be compensated electronically by the camera.

iv.This mode of operation improves the telescope’s observation efficiency and makes it more sensitive to faint and diffuse objects.

Note: The first image captured by the telescope consisted of several stars and a galaxy, NGC 4274, which is 45 million light years away.


i. The IMLT, which is installed at the Devasthal Observatory of ARIES, is the first liquid-mirror telescope designed exclusively for astronomical observations – photometric/astrometric direct imaging survey.

ii.The Devasthal Observatory now houses two 4-m class telescopes – the ILMT and the Devasthal Optical Telescope (DOT), both of which are considered to be the largest aperture telescopes available in India.

  • The 3.6 m DOT will allow rapid follow-up observations of newly found transient sources with the adjacent ILMT, using sophisticated back-end sensors.
  • Big Data and Artificial Intelligence/Machine Learning (AI/ML) algorithms will be implemented for classifying the objects observed with the ILMT.


The ILMT collaboration includes researchers from ARIES in India, the University of Liège and the Royal Observatory of Belgium in Belgium, Poznan Observatory in Poland, the Ulugh Beg Astronomical Institute of the Uzbek Academy of Sciences and National University of Uzbekistan in Uzbekistan, the University of British Columbia, Laval University, the University of Montreal, the University of Toronto, York University and the University of Victoria in Canada.

About Aryabhatta Research Institute of Observational Sciences (ARIES):

ARIES is one of the leading research Institutes which specializes in observational Astronomy & Astrophysics and Atmospheric Sciences.
Located – Nainital, Uttarakhand
Establishment – 2004
Director – Dipankar Banerjee