LiquidMirror Telescope

World’s first Liquid Mirror Telescope comes to India, sees first light in the Indian Himalayas

In a new feat achieved, India’s first liquid-mirror telescope has been commissioned at Devasthal, a hill in Uttarakhand which will be responsible to keep an eye on the overhead sky to identify transient or variable objects such as supernovae, gravitational lenses, space debris and asteroids.

The new telescope facility atop a mountain in the Himalayan range has seen its first light from an altitude of 2,540 metres. It has now entered the commissioning phase and will start scientific observations sometime in October this year.  




A unique Liquid-Mirror Telescope

It is fascinating to note that this telescope is the first Liquid-Mirror Telescope in the country and the largest in Asia. This unique telescope is commissioned to aid 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.



Established at the Devasthal Observatory campus of Aryabhatta Research Institute of Observational Sciences (ARIES), the telescope is 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.

How does it work?

The scientists from the three countries spun a pool of mercury which is a reflective liquid so that the surface curved into a parabolic shape which is ideal for focusing light. A thin transparent film of mylar protects the mercury from the 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.

According to Prof. Paul Hickson who is an expert on liquid mirror technology from the University of British Columbia, Canada, stated, “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.”

International Liquid Mirror Telescope

Professor Dipankar Banerjee, Director of ARIES informed that the International Liquid Mirror Telescope is the first liquid-mirror telescope designed exclusively for astronomical observations. He also mentioned that Devasthal Observatory now hosts two four-meter class telescopes – the ILMT and the Devasthal Optical Telescope (DOT). Both are the largest aperture telescopes available in the country.

“The wealth of data generated with the ILMT survey will be exemplary. In the future, several young researchers will be working on different science programs utilizing the ILMT data,” said Dr Kuntal Misra, who is the Project Investigator of ILMT at ARIES. “When regular science operations begin later this year, the ILMT will produce about 10 GB of data every night, which will be quickly analyzed to reveal variable and transient stellar sources,” said Dr Brajesh Kumar, ILMT Project Scientist at ARIES. The 3.6 metre DOT, with the availability of sophisticated back-end instruments, will allow rapid follow-up observations of the newly-detected transient sources with the adjacent 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 the 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. The telescope was designed and built by the Advanced Mechanical and Optical Systems (AMOS) Corporation and the Centre Spatial de Liège in Belgium.