NLST- National Large Solar Telescope

 solar telescope  Add category

 Upload a photo

This observatory is the site for ‘National Large Solar Telescope’. This is supposed to be the world’s largest solar telescope with diameter of 2 m. Solar telescopes are special-purpose scientific instruments used to study the sun. They are among the biggest fixed telescopes and are equipped with an optical flat mirror system to track the sun rays and direct them on to the telescope. The solar telescope can study particles, which are spread across 50 km on the sun.



Though the 10-metre optical telescope at Mauna Kea in Hawaii is the largest, the Indian instrument will be the largest among solar telescopes.

Currently, the world's largest solar telescope is the McMath-Pierce Solar Telescope, with a diameter of 1.6 metres in Kitt Peak National Observatory at Arizona in the US.

Initially, three sites - at Hanle and Merak in the Ladakh region and Devasthal near Nainital, Uttarakhand - were explored to set up the telescope. Hanle in Ladakh, at an altitude of 4500 m; Merak village by the Pangong Lake, Ladakh at an altitude of 4350 m, and Devesthal in the central Himalayan region at an altitude of 2500 m.

Most of the equipment at this site at that time was for weather research for site selection. Extensive site characterization for the last two years has revealed that the seeing conditions in Ladakh region are better than those in Devesthal, as Ladakh is unaffected by monsoon and provides almost uninterrupted clear skies. The conditions at Hanle and Merak were found to be similar in terms of seeing, but strong unfavourable afternoon winds were observed at Hanle. Thus, Merak with around 1700 h of annual sunshine hours, stable east-west winds of a few metres per second, and low water-vapour content needed for infrared observations was identified as the most suitable deployment location for NLST. The flat land in the south allows for access to southern declinations and the land incursions surrounded by water provide stable atmospheric conditions (the advantages of lake sites come from the fact that over water, evaporation occurs simultaneously with cooling, which provides a natural temperature inversion that reduces local refractive index fluctuations).

Also, Pangong Lake is declared as a ‘wetland of International Importance’ under Ramsar Convention. So the effect of this project over the surrounding flora and fauna has to be measured. The Convention on Wetlands of International Importance, called the Ramsar Convention, is an intergovernmental treaty that provides the framework for national action and international cooperation for the conservation and wise use of wetlands and their resources.

The Ramsar Convention is the only global environmental treaty that deals with a particular ecosystem. The treaty was adopted in the Iranian city of Ramsar in 1971 and the Convention's member countries cover all geographic regions of the planet.

Pangong Lake is one of the largest brackish lakes in Asia that has been recognized as an important high altitude wetland habitat. It lies on the migratory route of many birds, including the elusive black-necked crane – the state bird of Jammu and Kashmir. IIA is conducting research to estimate the possible imprint of NLST on the local environment and bird species. The results of this research will be used to propose strategies which will ensure that the construction, as well as operational phases of the project can be undertaken with minimal disturbance to the local flora and fauna.

The National Large Solar Telescope (NLST) project is handled by the Bangalore-based Indian Institute of Astrophysics (IIA).

The project involves other scientific organisations such as the state-run Indian Space Research Organisation (ISRO), Aryabhatta Research Institute of Observational-Sciences, Tata Institute of Fundamental Research and Inter-University Centre, collaborating with German partners for the development of the telescope, its mechanical structure and back-end instrumentation. The IIA will be the nodal agency.