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.) Kalpana Palkhiwala
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