India Builds World’s Largest Telescope at the Highest Altitude: MACE

Cerenkov Effect

Cerenkov Effect (Photo credit: NRCgov)

By Kalpana Palkhiwala

New Delhi, April 18, 2013 (Washington Bangla Radio / PIB India): Major Atmospheric Cerenkov Experiment Telescope or MACE Hanle, is the world's largest telescope at the highest altitude being established at Hanle, Ladakh. It is being built by ECIL, Hyderabad for BARC. It will be built in Hyderabad and will be assembled at the campus of Indian Astronomical Observatory at Hanle. It will be remotely operated and will run on Solar Power.

It will help to explore the exciting energy range of gamma ray energy region in between satellite and the traditional Atmospheric Cerenkov experiments. The telescope is named after the Russian scientist Cerenkov who predicted that charged particles moving at high speeds in a medium, emit light.

According to Dr Tushar P Prabhu, Professor in-charge at Hanle, Indian Institute of Astrophysics, Bangalore will conduct experiments. IIA in collaboration with Tata Fundamental Research Institute (TIFR), demonstrated the advantages of high altitude by installing High Altitude Energy Gamma Ray (HAGAR) Telescope.

High energy gamma rays emitted from black hole or centers of galaxies, compact objects like pulsars  in our galaxy get absorbed in the atmosphere and do not reach the land. But when these rays interact with the atmosphere, the photons give rise to electron–positron pairs and there is a cascade of particles. When the particles move in the atmosphere at very high speed, they give rise to Cerenkov radiation. The blue and ultraviolet Cerenkov light is observed to infer the number of gamma rays hitting the atmosphere.

The gamma rays are high energy processes in the universe. Their study will help to understand study of high energy physics close to black holes, compact objects, dark matter  and high gravitational fields.

The advantage of high altitude is that the Cerenkov radiation due to gamma-rays which  normally occurs at 10 km altitude above sea level, will be at 5.5 km above ground,  almost half the distance from the telescope. The intensity of radiation on the ground will be four times higher. A smaller facility in such place will be sufficient to achieve what a bigger facility will do closer to sea level. Telescopes of HAGAR were fabricated in Bangalore and the detectors in the focal plane were built in TFIR laboratories at Mumbai. In 2008 HAGAR saw the first light, and observations are continuing thereafter.

One of the important observations was of a galaxy with an active nucleus where the activity increases occasionally due to processes in matter falling on the black hole.

The Himalayan Chandra Telescope (HCT) at Hanle, has discovered three galaxies with super massive black holes out of observation of 10 galaxies. The other important discoveries of the telescope include subtle differences between different supernovae explosions and new variable stars forming in our galaxy. The HCT also successfully discovered a number of low metallicity stars.

The 2-m aperture optical-infrared telescope, HCT, was installed in 2000 and started its   operation remotely since 2001.The telescope is equipped with 3 science instruments which are mounted on an instrument cube at the cassegrain focus of the telescope. The instruments available are the Himalayan Faint Object Spectrograph (HFOSC), the near-IR image, and the optical CCD imager. The remote operations make easy for astronomers to work without travelling to the remote high altitude site. Astronomers from all over the world and from other countries are using this.

(PIB Feature.)

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