India gets first liquid mirror telescope to survey sky
By Our Special Correspondent
New Delhi: A few weeks ago, villagers in Maharashtra were awe-struck with their skyline, wondering if the sight was remnants of long-distance missile, space debris or asteroids. In the absence of capability, there had not been definitive and conclusive findings of such events, leaving people to run their imagination as wild as possible.
But soon, the people will exactly know what did they see in their skyline. They will even know details of any transient objects.
India has just installed the first liquid telescope to survey the sky and space. The facility is a three-nation scientists’ efforts, which has been commissioned at Devasthal, a hill in Uttarakhand.
The telescope will generate 10 GB data each day to help the space scientists decipher the significance of the events seen in the sky and beyond.
It will keep a watch on the overhead sky to identify transient or variable objects such as supernovae, gravitational lenses, space debris, and asteroids, said the Ministry of Science in an official statement on Thursday.
The telescope will help 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.
It is the first liquid mirror telescope in the country and the largest in Asia.
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.
The telescope is located 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) in Nainital district, Uttarakhand.
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 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.
Prof. Paul Hickson (University of British Columbia, Canada), an expert on liquid mirror technology, said: “The rotation of the earth causes the images to drift across the camera, but this motion is compensated electronically by the camera.”
The telescope will capture even sensitive to faint and diffuse objects, he added.
Prof. Dipankar Banerjee, Director, ARIES said that Devasthal Observatory now hosts two four-meter class telescopes – the liquid mirror telescope and the Devasthal Optical Telescope (DOT).
Both are the largest aperture telescopes available in the country.
Prof. Banerjee is also enthusiastic about the application of Big Data and Artificial Intelligence/Machine Learning (AI/ML) algorithms that will be implemented for classifying the objects observed with the ILMT.
He stated, “I am hopeful that this project will attract and motivate several young minds from scientific and engineering backgrounds to take up challenging problems.”
“The wealth of data generated with the liquid mirror telescope will be exemplary. In future, several young researchers will be working on different science programs utilizing its data,” said Dr. Kuntal Misra, who is the Project Investigator.
“When regular science operations begin later this year, the telescope 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, 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.
“The data collected will be ideally suited to perform a deep photometric and astrometric variability survey over a period of typically five years,” said Project Director Prof. Jean Surdej (University of Liège, Belgium and University of Poznan, Poland).
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