Liquid mirror telescope in Devasthal sees first light

Once trained using AI tools, the telescope can help track transients such as supernovas, space debris and meteorites

Once trained using AI tools, the telescope can help track transients such as supernovas, space debris and meteorites

The four-meter International Liquid Mirror Telescope (ILMT) recently saw its first light, gazing into the deep sky from its vantage point on Devasthal, a hill in Uttarakhand.

Staring at the sky above it, the telescope will enable sky surveys and acquire images that can help observe transient phenomena such as supernovas and record the presence of space debris or meteorites — essentially looking at the sky. Built by a collaboration of scientists from Canada, Belgium and India, the telescope is located at an altitude of 2,450 meters on the Devasthal Observatory campus of the Aryabhata Research Institute of Observational Sciences (ARIES) in Nainital District, an autonomous institute under the Ministry of Science and Technology, Government of India.

A large pool of mercury placed in a vessel is spun so quickly that it takes on a parabolic shape. Since mercury is reflective, this shape helps focus the reflected light. A thin layer of mylar protects the mercury from the wind.

“It was exciting to see the primary mirror forming. Almost 50 liters of mercury, weighing almost 700 kilograms, is spun hard to form a paraboloid mirror just 4 mm thick and about 4 meters in diameter,” said Kuntal Misra, project researcher at ARIES. She has been working on this project since January 2020.

First image

The telescope’s first image consisted of several stars and a galaxy NGC 4274 located 45 million light-years away. The telescope, with a primary mirror that is liquid, cannot be turned and pointed in any direction. It “stars” at the zenith and looks at the sky as the Earth rotates, viewing different objects. This property can be used to scan and survey the sky, detect transients and moving objects such as meteorites. It will work in conjunction with the existing 3.6 meter long Devasthal optical telescope.

Once it starts making observations, the telescope collects gigabytes of data, which must be analyzed using artificial intelligence and machine learning (AI and ML) tools. “In a nighttime observation it will create thousands of images that cannot be analyzed just by looking at them. We will have to develop and train AI and ML tools for this,” said Dipankar Banerjee, director of the ARIES Observatory.

Since seeing the first light is on the trail of the monsoon, the real sightings may be, according to Dr. Banerjee only start in October, after the rain.


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