Trans- Himalayan region becoming one of the promising astronomical sites globally

What is the news?

A recent study said that the Indian Astronomical Observatory (IAO) located at Hanle near Leh in Ladakh is becoming one of the promising observatory sites globally. This is due to its advantages of more clear nights, minimal light pollution, background aerosol concentration, extremely dry atmospheric condition, and uninterrupted by monsoon.

About the study

Astronomers are constantly searching for ideal locations around the world to build their next big telescope based on local meteorological data collected over many years. Such studies are crucial in planning for future observatories and the prediction of how they will vary with time.

Researchers led by the Indian Institute of Astrophysics (IIA), Bangalore, carried out a detailed study of the nighttime cloud cover fraction over 8 high altitude observatories, including three in India. The Indian locations include Indian Astronomical Observatory (IAO) in Hanle and Merak (Ladakh), and Devasthal (Nainital) in India.

The study classified the quality of observable nights for different astronomical usages like photometry and spectroscopy on a daily basis.

What are the key findings of the study?

The researchers found decreasing trends for the cloud cover fraction over the central region of Africa, the Eurasian continent, and the American continents. On the other hand, the researchers found increasing trends in the maritime region as well as land regions in the Sahara Desert, the Middle East, Indian sub-continent, the Tibetan Plateau and some of the Southeast Asian islands. his was possibly caused by global warming and associated water vapour changes in land-oceanic regions.

The researchers found that Paranal, located in a high-altitude desert in Chile, to be the best site in terms of clear skies with around 87% of clear nights in a year.

The researchers found that the Hanle site is as dry as the Atacama Desert in Chile and much drier than Devasthal. The Hanle has around 270 clear nights in a year and is also one of the emerging sites for infrared and sub-mm optical astronomy. This is because water vapour absorbs electromagnetic signals and reduces their strength.

About Indian Astronomical Observatory (IAO)

It is located in Hanle near Leh in Ladakh. It is operated by the Indian Institute of Astrophysics, Bangalore. The IAO currently hosts Telescopes such as the Himalayan Chandra Telescope, GROWTH-India Telescope, High Altitude Gamma Ray Telescope.

Source:  This post is based on the article “Trans- Himalayan region becoming one of the promising astronomical sites globally” published in PIB on 30th September 2021.

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