Trans-Himalayan region among promising astronomical sites worldwide: Study

The Ministry of Science and Technology, in its latest report, has revealed that the Indian Astronomical Observatory (IAO) located at Hanle near Leh in Ladakh is becoming one of the promising observatory sites globally. Space enthusiasts and primarily scientists are constantly searching for the ideal locations worldwide from where they can carry out astronomical studies. As per the ministry, it recorded this higher influx of astronomers based on assimilation and observation of data extending over 41 years.

Factors causing the influx

According to the press release by the ministry, factors like a higher number of clear nights, minimal light pollution, background aerosol concentration, extremely dry atmospheric condition, and less interruption by monsoon has attracted the crowd. Such conditions are considered crucial for astronomers to build huge telescopes and plan for future observatories and predict how they will vary with time. As per the release, the research was led by Dr Shantikumar Singh Ningombam of Bengaluru’s IIA along with scientists from Nainital’s ARIES, Department of Science & Technology, the Government of India, and collaborators from South Korea and even the US. The researchers analysed data that spanned 41 years, including 21 years of satellite data. Besides, they also carried out a detailed study of the nighttime cloud cover fraction over eight high altitude observatories, including three in India.

The ministry revealed that the eight sites included IAO’s Hanle and 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, and Mexico’s National Astronomical Observatory. The findings suggested that the Hanle site has around 270 clear nights in a year and is also one of the emerging sites for infrared and sub-mm optical astronomy despite being as dry as the Atacama Desert in Chile and much drier than Devasthal.

Moreover, they found that IAO-Hanle, and Ali observatories, are similar to each other in terms of clear night skies as both are located only around 80 km from each other. Chile’s Paranal won in terms of clear skies with approximately 87% of clear nights in a year. Revelations from the satellite data at different time resolutions also showed that the cloud cover fraction for Hanle, Merak, and Devasthal in India and Ali in China were 66-75%, 51-68%, 61-78%, and 61-75%. Studies of meteorological parameters like these would be highly beneficial for the IIA as it is planning on several mega-science projects such as the National Large Solar Telescope (NLST) of 2-meter aperture and the National Large Optical Telescope (NLOT) of 8-10 meter aperture at Merak and Hanle, said the ministry.

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