Context: A new study shows that the Indian Astronomical Observatory (IAO) located in Hanle is one of the emerging sites for infrared and optical astronomy studies.
About Hanle site 

• It is as dry as the Atacama Desert in Chile and much drier than Devasthal (Uttarakhand) and 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.
• It has advantages of more clear nights, minimal light pollution, background aerosol concentration, extremely dry atmospheric conditions, and uninterrupted monsoon.
• Such conditions are considered crucial for astronomers to build huge telescopes and plan for future observatories and predict how they will vary with time.

Major telescopes at Hanle include

1. Himalayan Chandra Telescope (An optical-infrared telescope named after India-born Nobel laureate Subrahmanyam Chandrasekhar)
2. GROWTH-India Telescope (A robotic optical telescope)
3. High Altitude Gamma Ray Telescope

Other Promising Sites

• Merak observatories in Ladakh.
• Devasthal in Nainital, Ali Observatory in the Tibet Autonomous Region in China.
• South African Large Telescope in South Africa.
• University of Tokyo Atacama Observatory and Paranal in Chile.
• Mexico’s National Astronomical Observatory.