Indian Astronomical Observatory

Recently, in a first-of-its-kind initiative, the Department of Science & Technology (DST) has announced the setting up of India’s first Dark Sky Reserve in Hanle, Ladakh.

What is a ‘Dark Sky Reserve’?

• Description — It is a designation given to a place that has policies in place to ensure that a tract of land or region has minimal artificial light interference.
• Designated areas — These are areas that offer exceptional starry nights and are specifically protected for scientific, natural, educational, cultural, heritage and/or public enjoyment.
• Accreditation — It is designated by the U.S.-based non-profit, International Dark-Sky Association (IDA) since 1988.

Background of Indian Astronomical Observatory –

• Discovery — Indian astronomers in India, led by R. Rajamohan, discovered an asteroid that was later named 4130 Ramanujan. It was the first time in 104 years that asteroids were discovered from India.
• Location — Their instrument, the 45-cm Schmidt telescope, was housed on the Javadi hills in Kavalur, Tamil Nadu and the spot is today called as Vainu Bappu Observatory. It is today run by the Indian Institute of Astrophysics (IIA), Bengaluru, and is among India’s foremost observatories.
• Reasoned choice — It was chosen in the 1960s because it was at impressive 750 metres above sea level, located amid a forest and offered fairly unobstructed vistas of the night sky.
• Not ideal spot — Kavalur’s geography put it in the path of both monsoonal clouds, during June-September and the returning, or northeast monsoon in November, forcing the observatory to often shut down for months.
  • • Also, rainclouds absorb starlight and radiation from cosmic objects, preventing them from being caught on the telescopes of cameras. Hence, the search began in the early 1980s for a place least affected by the monsoon.

The Hanle Observatory –

• A dry, high-altitude desert is in many ways was an ideal location, but such terrain is difficult and quite inaccessible. However, after several expeditions to different parts of the Himalayas finally Hanle (Ladakh) was chosen.
• Location — The Indian Astronomical Observatory stands on Saraswati, Hanle in south-eastern Ladakh union territory at an altitude of 14,000 ft above sea level .
• Climatic conditions — Hanle site is as dry as the Atacama Desert in Chile and much drier than Devasthal (Uttarakhand) and has around 270 clear nights in a year.
• Set-up — The Indian Astronomical Observatory here at Hanle has one of the world’s highest sites for optical, infrared and gamma-ray telescopes.
• Optimal conditions — According to the Department of Science and Technology, this is due to its advantages of —
  • • Clear nights
    • Minimal light pollution
    • Background aerosol concentration
    • Extremely dry atmospheric condition
    • Uninterrupted monsoon
• Also, such conditions are considered crucial for astronomers to build huge telescopes and plan for future observatories and predict how they will vary with time.
• Global standing — Termed as the Major Atmospheric Cherenkov Experiment Telescope (MACE), located near Hanle, it is currently the ninth highest optical telescope in the world and is operated by the Indian Institute of Astrophysics, (IIA) Bangalore.
  • • MACE is built by a consortium of the Bhabha Atomic Research Centre, the Tata Institute of Fundamental Research, the Electronics Corporation of India Ltd. and the IIA.
    • The goal of MACE is to detect Cherenkov radiation from space.
    • This is a special kind of light from gamma rays, or the most energetic sources of radiation, that can result from dying stars or several galactic events.
• Himalayan Chandra Telescope (HCT) — It is the metallic capsule, the highest of the observatories, the oldest and active since 2000.
  • • It is an optical-infrared telescope with a 2-metre lens, designed to detect light from the visible range of the electromagnetic spectrum as well as that just below it, or the infra-red spectrum.
    • The second capsule, situated slightly lower than the HCT, is the GROWTH-India telescope, a 70-cm telescope made by IIA and IIT Mumbai is equipped to track cosmic events, such as afterglows of a gamma ray burst or tracking the path of asteroids.
• A High Altitude Gamma Ray Telescope (HAGAR) — It is an array of seven telescopes, operational since September 2008 and constitutes the first phase of the Himalayan Gamma-Ray Observatory (HIGRO) project. It also looks at Cherenkov radiation, although at a lower range of energies.