Indian Astronomical Observatory

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Indian Astronomical Observatory
Hanle observatory.jpg
Indian Astronomical Observatory, Hanle
Organization Indian Institute of Astrophysics
Location Hanle, India
Altitude 4,500 m (14,764 ft)
Established 2001
Indian Astronomical Observatory
Himalayan Chandra Telescope 2.01 m Ritchey-Chretien, remotely operated optical-infrared telescope
HAGAR Gamma Ray Telescope

The Indian Astronomical Observatory (IAO), located near Leh in Ladakh, India, has one of the world's highest sites for optical, infrared and gamma-ray telescopes. It is operated by the Indian Institute of Astrophysics, Bangalore. It is currently the second highest optical telescope in the world, situated at an elevation of 4,500 meters (14,764 ft).


The Indian Astronomical Observatory stands on Mt. Saraswati, Digpa-ratsa Ri, Hanle in south-eastern Ladakh in the eastern Jammu and Kashmir state of India.[1] Accessing the observatory, located near the Chinese border, requires a ten-hour drive from Leh, the district capital of Ladakh.[2]


In the late 1980s a committee chaired by Prof. B. V. Sreekantan recommended that a national large optical telescope be taken up as a priority project. The search for the site of the observatory was taken up in 1992 under the leadership of Prof. Arvind Bhatnagar. The scientists from the Indian Institute of Astrophysics found the site at Hanle.[3]

The first light was seen by the Observatory 2-metre telescope on the midnight hour between September 26 and September 27, 2000.[1]

The satellite link between the Centre for Research and Education in Science and Technology (CREST), Bangalore and Hanle was inaugurated by the then Jammu and Kashmir Chief Minister Dr. Farooq Abdullah on June 2, 2001. The Observatory was dedicated to the nation on August 29, 2001.[4]


The hanle site is deemed to be excellent for visible, infrared and submillimeter observations throughout the year.[2] Specifically the observation conditions yield about 255 spectroscopic nights per year, approximately 190 photometric nights per year and an annual rain plus snow precipitation of less than 10 cm. In addition, there are low ambient temperatures, low humidity, low concentration of atmospheric aerosols, low atmospheric water vapour, dark nights and low pollution.[1]


The Observatory has two active telescopes. These are the 2.01 meter optical-infrared Himalayan Chandra Telescope (HCT) and a High Altitude Gamma Ray Telescope (HAGAR). The HCT is remotely operated from Bangalore from the Centre for Research and Education in Science and Technology (CREST) using a dedicated satellite link.

Himalayan Chandra Telescope[edit]

The Himalayan Chandra Telescope is a 2.01 meters (6.5 feet) diameter optical-infrared telescope named after India-born Nobel laureate Subrahmanyam Chandrasekhar.[2] It contains a modified Ritchey-Chretien system with a primary mirror made of ULE ceramic which is designed to withstand low temperatures it experiences.[5] The telescope was manufactured by Electo-Optical System Technologies Inc. at Tucson, Arizona, USA. The telescope is mounted with 3 science instruments called Himalaya Faint Object Spectrograph (HFOSC), the near-IR imager and the optical CCD imager.[2][6] The telescope is remotely operated via an INSAT-3B satellite link which allows operation even in sub-zero temperatures in winter.[5]

High Energy Gamma Ray Telescope (HAGAR), Hanle

High Altitude Gamma Ray Telescope[edit]

The High Altitude Gamma Ray Telescope (HAGAR) is an atmospheric Cerenkov experiment with 7 telescopes setup in 2008.[7] Each telescope has 7 mirrors with a total area of 4.4 square meters. The telescopes are deployed on the periphery of a circle of radius 50 meters with one telescope at the center. Each telescope has alt-azimuth mounting.[8]

Center for Research and Education in Science and Technology[edit]

The Center for Research and Education in Science and Technology (CREST) is situated 35 km to the northeast of Bangalore near Hoskote town. The Center houses the control room for the remote operations of the 2m Himalayan Chandra Telescope (HCT) at the Indian Astronomical Observatory, Hanle, and the HCT data archive. The operations are controlled using a remote satellite link.[9]

Upcoming facilities[edit]

The Indian Institute of Astrophysics is collaborating with the McDonnell Center for the Space Sciences of Washington University in St. Louis, USA to operate two 0.5 meters Cassegrain telescopes to monitor active galactic nuclei. One of the observatories is to be established in Hanle.[2] The facilities 180 degrees apart in longitude are together to be called the Antipodal Transient Observatory (ATO).[10]

A Himalayan Gamma Ray Observatory (HiGRO) is being set up at Hanle in collaboration with Tata Institute of Fundamental Research, Mumbai and Bhabha Atomic Research Centre, Mumbai. This is currently in the advanced stage of commissioning and is expected to be functional by 2018.

The Major Atmospheric Cerenkov Experiment (MACE) is also expected to be set up here by December 2012.[11] The Experiment expects to have a 21 meter collector which can collect gamma rays from space.[11] The effort to establish the facility is led by Bhaba Atomic Research Center in collaboration with Tata Institute of Fundamental Research, Indian Institute of Astrophysics, Bangalore and Saha Institute of Nuclear Physics, Kolkata. The facility is estimated to cost Rs. 40 crores.[11] Once completed it will be the only such facility in the eastern hemisphere.[11]

See also[edit]


  1. ^ a b c News, Dec 25, 2000, Vol. 79 No. 12 Current Science, Indian Academy of Sciences
  2. ^ a b c d e Pallava Bagla (January 7, 2002) "India Unveils World's Highest Observatory", National Geographic News, Retrieved January 21, 2011
  3. ^ Rajan, Mohan Sundara. "Telescopes in India". National Book Trust, India, 2009, p. 132
  4. ^ About IAO, IAO website. accessed on January 20, 2011.
  5. ^ a b Ravi Sharma (Volume 18 - Issue 20, Sep 29 - Oct 12, 2001), "A stellar acquisition", Frontline; Retrieved on January 25, 2011
  6. ^ IAO Telescope Accessed on January 21, 2011
  7. ^ Staff Reporter (December 13, 2009) "Plan to establish Indian Neutrino observatory", The Hindu, Retrieved on January 21, 2011
  8. ^ Hagar Telescope Accessed on January 21, 2011
  9. ^ CREST Accessed on January 21, 2011
  10. ^ Antipodal Transient Observatory. Accessed on January 20, 2011
  11. ^ a b c d Sunderarajan, P (17 June 2011). "Gamma ray telescope getting ready at Hanle". The Hindu. Retrieved 17 June 2011. 

External links[edit]