The Indian Astronomical Observatory (IAO) is a high-altitude astronomy station located in Hanle, India and operated by the

Indian Institute of Astrophysics The Indian Institute of Astrophysics (IIA), with its headquarters in Bengaluru,is an autonomous Research Institute wholly financed by the department of Science and Technology, Government of India. IIA conducts research primarily in the areas of ...

. Situated in the Western Himalayas at an elevation of 4,500 meters (14,764 ft), the IAO is one of the world's highest located sites for

optical Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviole ...

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

and gamma-ray telescopes. It is currently the tenth (see

List of highest astronomical observatories This is a list of the highest astronomical observatories in the world, considering only ground-based observatories and ordered by elevation above mean sea level. The main list includes only permanent observatories with facilities constructed at ...

) highest optical telescope in the world. It is India's first

dark-sky preserve A dark-sky preserve (DSP) is an area, usually surrounding a park or observatory, that restricts artificial light pollution. The purpose of the dark-sky movement is generally to promote astronomy. However, astronomy is certainly not the only obje ...

.All you need to know about India's first dark sky reserve in Ladakh
Business Standard, Karthik Jerome, 9 September 2022.

Location

The Indian Astronomical Observatory stands on Mt. Saraswati, Digpa-ratsa Ri, Hanle in south-eastern

Ladakh Ladakh () is a region administered by India as a union territory which constitutes a part of the larger Kashmir region and has been the subject of dispute between India, Pakistan, and China since 1947. (subscription required) Quote: "Jammu and ...

union territory of India.News
Dec 25, 2000, Vol. 79 No. 12 Current Science
Indian Academy of Sciences Accessing the observatory, located near the Chinese border (

Line of Actual Control The Line of Actual Control (LAC), in the context of the Sino-Indian border dispute, is a notional demarcation lineAnanth KrishnanLine of Actual Control , India-China: the line of actual contest, 13 June 2020: "In contrast, the alignment o ...

), requires a 250 km long ten-hour drive from

Leh Leh () ( lbj, ) is the joint capital and largest city of Ladakh, a union territory of India. Leh, located in the Leh district, was also the historical capital of the Kingdom of Ladakh, the seat of which was in the Leh Palace, the former res ...

city, the headquarter of Leh district.

Nyoma Nyoma is a principal village of southern Ladakh in India, the headquarters of an eponymous subdivision, tehsil and community development block in the Leh district.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. The first light was seen by the Observatory 2-metre telescope on the midnight hour between 26 September and 27 September 2000. 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 2 June 2001. The Observatory was dedicated to the nation on 29 August 2001.

Observation: Dark-sky preserve

In September 2022, it became India's first

. The Hanle site is deemed to be excellent for visible, infrared and

submillimeter Submillimetre astronomy or submillimeter astronomy (see spelling differences) is the branch of observational astronomy that is conducted at submillimetre wavelengths (i.e., terahertz radiation) of the electromagnetic spectrum. Astronomers plac ...

observations throughout the year. 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.

Facilities

The Observatory has several active telescopes. These are the 2.01 meter optical-infrared Himalayan Chandra Telescope (HCT), a High Altitude Gamma Ray Telescope (HAGAR), and . 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 (HCT)

The Himalayan Chandra Telescope is a 2.01 meters (6.5 feet) diameter optical-infrared telescope named after India-born Nobel laureate Subrahmanyam Chandrasekhar.Pallava Bagla (7 January 2002)
India Unveils World's Highest Observatory
, National Geographic News, Retrieved 21 January 2011 It contains a modified Ritchey-Chretien system with a primary mirror made of ULE ceramic which is designed to withstand low temperatures it experiences. 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. The telescope is remotely operated via an

INSAT-3B INSAT-3B is an Indian communications satellite which was built by the Indian Space Research Organisation and operated by Indian National Satellite System. Overview INSAT–3B is the first satellite built under INSAT–3 series of satellites to ...

satellite link which allows operation even in sub-zero temperatures in winter.Ravi Sharma (Volume 18 - Issue 20, 29 Sep - 12 Oct 2001), , ''Frontline''; Retrieved on 25 January 2011 IAO-Hanle-high energy gamma ray telescope-UnderRainbow

IAO-Hanle-high energy gamma ray telescope-UnderRainbow

GROWTH-India Telescope

The GROWTH-India telescope is a 0.7 meter wide-field optical telescope that had first light in 2018. It is the country's first fully robotic research telescope. It was set up as a part of the international GROWTH program, and has been widely used for time domain astronomy. The telescope is operated jointly by

IIT Bombay The Indian Institute of Technology Bombay (IIT Bombay or IITB) is a public research university and technical institute in Powai, Mumbai, Maharashtra, India. It is considered as one of the best engineering universities in India and is top ranked ...

and the Indian Institute of Astrophysics.

IIA-Washington University Cassegrain telescope

Since 2011, the Indian Institute of Astrophysics (IIA) collaborates with the McDonnell Center for the Space Sciences of

Washington University Washington University in St. Louis (WashU or WUSTL) is a private research university with its main campus in St. Louis County, and Clayton, Missouri. Founded in 1853, the university is named after George Washington. Washington University is r ...

St. Louis St. Louis () is the second-largest city in Missouri, United States. It sits near the confluence of the Mississippi and the Missouri Rivers. In 2020, the city proper had a population of 301,578, while the bi-state metropolitan area, which e ...

in USA to operate two 0.5 meters Cassegrain telescopes to monitor

active galactic nuclei An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much-higher-than-normal luminosity over at least some portion of the electromagnetic spectrum with characteristics indicating that the luminosity is not prod ...

. One of the observatories is established in Hanle. The facilities 180 degrees apart in

longitude Longitude (, ) is a geographic coordinate that specifies the east–west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter l ...

are together to be called the Antipodal Transient Observatory (ATO).

High Altitude Gamma Ray Telescope

The High Altitude Gamma Ray Telescope (HAGAR) is an atmospheric Cerenkov experiment with 7 telescopes setup in 2008. 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. A Himalayan

Gamma Ray A gamma ray, also known as gamma radiation (symbol γ or \gamma), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves, typically ...

Observatory (HiGRO) was set up at Hanle in collaboration with

Tata Institute of Fundamental Research Tata Institute of Fundamental Research (TIFR) is a public deemed research university located in Mumbai, India that is dedicated to basic research in mathematics and the sciences. It is a Deemed University and works under the umbrella of the D ...

Mumbai Mumbai (, ; also known as Bombay — the official name until 1995) is the capital city of the Indian state of Maharashtra and the ''de facto'' financial centre of India. According to the United Nations, as of 2018, Mumbai is the second- ...

and

Bhabha Atomic Research Centre The Bhabha Atomic Research Centre (BARC) is India's premier nuclear research facility, headquartered in Trombay, Mumbai, Maharashtra, India. It was founded by Homi Jehangir Bhabha as the Atomic Energy Establishment, Trombay (AEET) in January 195 ...

, Mumbai.

Major Atmospheric Cerenkov Experiment Telescope Major Atmospheric Cerenkov Experiment Telescope (MACE) is an Imaging Atmospheric Cerenkov telescope (IACT) located near Hanle, Ladakh, India. It is the highest (in altitude) and second largest Cerenkov telescope in the world. It was built by El ...

(MACE) was set up here in December 2012. The Experiment has a 21-meter collector which can collect gamma rays from space. The facility is a result of initiative led by

in collaboration with

Bangalore Bangalore (), officially Bengaluru (), is the capital and largest city of the Indian state of Karnataka. It has a population of more than and a metropolitan population of around , making it the third most populous city and fifth most ...

and

Saha Institute of Nuclear Physics The Saha Institute of Nuclear Physics (SINP) is an institution of basic research and training in physical and biophysical sciences located in Bidhannagar, Kolkata, India. The institute is named after the famous Indian physicist Meghnad Saha. ...

Kolkata Kolkata (, or , ; also known as Calcutta , the official name until 2001) is the capital of the Indian state of West Bengal, on the eastern bank of the Hooghly River west of the border with Bangladesh. It is the primary business, comme ...

. The facility cost in 2011 was Rs. 400 million. As of 2011, it was the first and only such facility in the

eastern hemisphere The Eastern Hemisphere is the half of the planet Earth which is east of the prime meridian (which crosses Greenwich, London, United Kingdom) and west of the antimeridian (which crosses the Pacific Ocean and relatively little land from pole to pol ...

. The telescope was fabricated by the

Electronics Corporation of India Electronics Corporation of India Limited (ECIL) ( ईलेक्ट्रॉनिक्स कॉर्पोरेशन ऑफ ईन्डिया लिमिटेड ( ) ) is a Public Sector Enterprise under the Department of Atomi ...

and was installed at the IAO in June 2014. This Telescope became the second largest gamma ray telescope in the world and the world's largest telescope at the highest altitude.

Center for Research and Education in Science and Technology

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.

Jantar Mantar, Jaipur The Jantar Mantar, Jaipur is a collection of 19 astronomical instruments built by the Rajput king Sawai Jai Singh II, the founder of Jaipur, Rajasthan. The monument was completed in 1734.National Centre for Polar and Ocean Research The National Centre for Polar and Ocean Research, (NCPOR) formerly known as the National Centre for Antarctic and Ocean Research (NCAOR) is an Indian research and development institution, situated in Vasco da Gama, Goa. It is an autonomous Insti ...

* Siachen Base Camp (India) *

List of Antarctic field camps Many Antarctic research stations support satellite field camps which are, in general, seasonal camps. The type of field camp can vary – some are permanent structures used during the annual Antarctic summer, whereas others are little more than te ...

* List of Antarctic research stations *

; Borders *

Actual Ground Position Line The Actual Ground Position Line (AGPL) divides current positions of Indian and Pakistani military posts and troops across the entire long front line in the disputed region of Siachen Glacier. AGPL generally runs along the Saltoro Mountains ra ...

(AGPL), India-Pakistan border across Siachen region *

(LAC), India-China border across Ladakh *

Line of Control The Line of Control (LoC) is a military control line between the Indian and Pakistanicontrolled parts of the former princely state of Jammu and Kashmir—a line which does not constitute a legally recognized international boundary, but serve ...

(LoC), India-Pakistan border across Ladakh and Jammu and Kashmir ; Conflicts *

Sino-Indian War The Sino-Indian War took place between China and India from October to November 1962, as a major flare-up of the Sino-Indian border dispute. There had been a series of violent border skirmishes between the two countries after the 1959 Tib ...

Indo-Pakistani wars and conflicts Since the Partition of India, Partition of British India in 1947 and subsequent creation of the dominions of Dominion of India, India and Dominion of Pakistan, Pakistan, the two countries have been involved in a number of wars, conflicts, and m ...

Siachen conflict The Siachen conflict, sometimes referred to as the Siachen Glacier conflict or the Siachen War, was a military conflict between India and Pakistan over the disputed Siachen Glacier region in Kashmir. The conflict was started in 1984 by India' ...

Siachen Glacier The Siachen Glacier is a glacier located in the eastern Karakoram range in the Himalayas at about , just northeast of the point NJ9842 where the Line of Control between India and Pakistan ends. At long, it is the longest glacier in the Kar ...

; Geography *

Geology of the Himalaya The geology of the Himalayas is a record of the most dramatic and visible creations of the immense mountain range formed by plate tectonic forces and sculpted by weathering and erosion. The Himalayas, which stretch over 2400 km between t ...

Indus-Yarlung suture zone The Indus-Yarlung suture zone or the Indus-Yarlung Tsangpo suture is a tectonic suture in southern Tibet and across the north margin of the Himalayas which resulted from the collision between the Indian plate and the Eurasian plate starting abo ...

List of districts of Ladakh The Indian union territory of Ladakh consists of two districts. Each district elects an autonomous district council. Until 31 October 2019, these districts were part of the former state of Jammu and Kashmir. List * Indicates area under the ...

; Tourism and infrastructure * India-China Border Roads * Siachen Base Camp (India) *

Tourism in Ladakh Tourism is one of an economic contributor to the union territory of Ladakh in Northern India. The union territory is sandwiched between the Karakoram mountain range to the north and the Himalayas to the south and is situated at the height ...

;Pre-independence * Nizamia observatory

References

External links

* Official Website
Indian Astronomical Observatory

2-m Himalayan Chandra Telescope with the 50-cm Antipodal Transient Observatory in the background

Bangalore scientists, techies to help build largest telescopes
{{Portal bar, India, Astronomy, Stars, Spaceflight, Outer space, Solar System, Education, Science Astronomical observatories in India Space programme of India Indian Institute of Astrophysics Buildings and structures in Ladakh Leh district Science and technology in Ladakh 2001 establishments in Jammu and Kashmir