It is a telescope like no other, a special robotic eye in the sky to track some of the most energetic phenomena such as the birth and death of stars. One needs very special instruments to study these exploding stars. India now holds the honour of having the world’s highest-altitude gamma ray telescope situated at 4,270 metres above sea level and it has the largest mirror in Asia.
The Department of Atomic Energy (DAE) established the Major Atmospheric Cherenkov Experiment or MACE. It is a cutting-edge gamma ray telescope for very high energy astronomy. It was developed by the Bhabha Atomic Research Centre (BARC), Mumbai and is installed at Hanle, Ladakh.
“Hanle is like heaven for gamma ray astronomers with its dark skies, low humidity and almost no air pollution,” said Dr AK Mohanty, chairman, Atomic Energy Commission and India’s nuclear chief.
He said another few more gamma ray telescopes could be built here, making Hanle the go-to place for global astronomers, some with international collaboration.
According to DAE, the MACE telescope, due to its high sensitivity, will be able to detect gamma rays from supernova remnants, pulsars and micro-quasars. It will also peep into the centres of distant galaxies hosting supermassive blackholes and will be able to discover the high-energy processes occurring around it. The MACE telescope will be used to search for dark matter in the universe and unravel its mysteries.
The event where locals participated in large numbers has been titled ‘Juley Cosmos’. “Juley” is a salutation used by Ladakhis, which the DAE says is made-in-India but made for the world. It is situated not far from the China border, some 250 km from Ladakh’s capital Leh.
The conceptualisation and design were carried out by the Astrophysical Sciences Division of BARC. The MACE telescope has been commissioned at Hanle, at an altitude of 4,270 metres above mean sea level. It is required to accurately position the large mechanical structure, having a 21-metre diameter reflector in less than three minutes. This requires careful selection of lightweight construction, approximately 175 tonnes, and simultaneously maintaining high strength and temperature endurance. Transport constraints in the Ladakh region restrict the size of sub-components to less than 2.5 metres.
Reflector surface measuring over 350 square metres (sqm) comprises highly reflective diamond-turned custom-built metallic mirror facets that are required to be aligned with an accuracy of 2 mm over parabolic surface. The camera at the focal point contains a number of photomultiplier tubes mounted with specialised assembly to enhance light collection efficiency.
Ultrafast backend electronics with nanosecond digitization electronics is optimised for low-power and -temperature operations. Extreme weather conditions restrict transport to six-eight months a year and affect the availability of trained personnel on site.
MACE is currently the largest Cherenkov telescope in Asia. It is the highest altitude observatory among similar facilities in the world. The site has been carefully chosen for its unique scientific advantages as Hanle offers extremely low light pollution required for gamma ray observations. The longitudinal advantage of its location enables MACE to observe sources invisible to other parts of the world.
MACE is 21 metres in diameter, 175 tonnes heavy, has reflector area of 356 sqm and 1,424 diamond-turned metallic mirror facets, 712 actuators, 1,088 photo-multiplier tubes, and 68 camera modules.
At the inauguration, Dr Annapurni Subramaniam, director of the Indian Institute of Astrophysics that is the host agency for the Indian Astronomy Observatory at Hanle, said, “The MACE telescope is an engineering marvel as it withstands the very high winds of Hanle.”
Even before its formal inauguration, the telescope produced high-quality work detecting gamma ray flares as far away as 200 million light years away and detected during observation on a freezing December night in 2022. This high-altitude telescope is the world’s envy and India’s pride.