India’s Liquid Mirror Telescope is ready for its close-up

The International Liquid Mirror Telescope in its building in the Himalayas.

The International Liquid Mirror Telescope in its building in the Himalayas.
Photo: John Surdej

High in the Himalayas, a new telescope is installed to observe the night sky. The craft has a 4-meter (13-foot) lens, but here’s the kicker: it’s made of liquid mercury, a material rarely used for astronomical imaging.

Called the International Liquid Mirror Telescope (ILMT for short), the main component of the device is a layer of liquid mercury which floats on a very thin layer of compressed air. Quicksilver rotates, taking on a parabolic shape in the process, useful for focusing light from the night sky. By placing a camera at the focus of the paraboloid, astronomers will then be able to image objects in the sky.

At first glance, the telescope mirror appears to be an ordinary reflective surface. But in reality, it’s made of liquid which was meticulously shipped up the mountain by a hazardous materials company. As long as nobody tries to drink the telescope mirror, however, is perfectly safe and, according to the ILMT team, an affordable alternative to other telescope mirror materials.

“The main advantage is the relatively low cost of a large liquid mirror compared to a conventional large telescope mirror,” said Paul Hickson, a University of British Columbia astronomer who works on liquid mirror technologies. , in an email to Gizmodo. “As an example, the cost of the ILMT is about one tenth of that of the 3.6 meter [11.8-foot] Devastating Optical Telescope — a conventional telescope of about the same size and located in the same place.

And this place is quite high. The telescope sits over 8,000 feet above sea level on the Indian side of the Himalayas. It will scan a band of sky directly overhead that contains hundreds of thousands of galaxies and several thousand quasars, Hickson said. (Quasars are very active galactic nuclei, which glow in the night sky.)

By imagining the sky at night – directly overhead, where there is the least atmospheric noise – astronomers can deduce what objects in the sky are changing over time, whether new supernovae , asteroids passing in front of luminous objects or even bending transiting black holes. the light of sources behind them.

“We estimated that 50 new cases of multi-image quasars should be detected in the field of view of the ILMT,” said Jean Surdej, an astrophysicist at the University of Liège in Belgium and director of the project, in an e- email to Gizmodo.

The telescope saw his first light in april, but scientific observations will not begin until later this year. When fully operational, the telescope will collect 10 gigabytes of data each night. Given the mercury nature of supernovae and gravitational lensing, it is normal for ILMT to capture these events with mercury.

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