MSV-2035 Astronomy Document - Inside Design - FINAL - FINAL

Astronomy & Astrophysics 62 MEGA SCIENCE VISION-2035 (optical = 22 mag) survey will approximately cover 50 square degrees at high galactic latitudes, which is very useful for gravitational lensing studies as well as for the discovery of various classes of interesting extragalactic objects (cf. newquasars, supernovae, clusters, etc.). Utilisation and requirement: The existing optical/IR facilities are well utilised by the community. The 1-meter telescopes at VBO and Nainital that were established in the early 1970s are still being used, as is also the 1.2-meter PRL telescope. The 2-meter HCT and the 3.6-meter DOT have around 300 users and are oversubscribed by a factor of 2-3 on an average. The HCT has proved to be a very productive telescope with over 350 refereed publications, and nearly 70 Ph.D. theses that have used data obtained with the telescope. The two 1.3-meter telescopes are being utilised very effectively in long term monitoring of AGN variability, transits of exo-planets and observations of transients, GRB sources in particular. TheARIES 1.3-meter telescope is also used for Lunar occultation observations. All the existing facilities are yielding good science, however, the size of the telescopes limits their capability to the studies of relatively brighter, nearby sources. None of the recent facilities match the global initiatives undertaken in the past two decades. The optical-IR telescopes in India as compared to those available globally are summarised in a chronological manner inTable 1. It is clear from the table that India is far behind the rest of the world as far as access to state-of-the-art optical astronomy facilities are concerned. Not only in terms of the telescope aperture, but also in terms of advanced technology instruments. For India, the best way to catch up with the rest of the world is to participate in existing large facility programmes, as well as in multinational efforts to build mega-facilities, and through which the necessary technical skills to create large facilities within the country, such as a 10-meter class telescope with state-of-the-art and innovative instruments, can be established. Asmall fraction of Indian astronomers have access to the 12-meter SouthernAfrican Large Telescope (SALT) located in SouthAfrica, through IUCAA, which is a partner at 6% level. Through this partnership, scientists and engineers at IUCAA are contributing to the development of new technology instruments, bringing in experience in fibre-fed instruments, in a limited way. A larger-scale, national-level participation in an existing 10-meter class telescope will bring a wider experience in the generation of globally competitive science using state-of-the-art instruments. India is partnering to build a 30-meter telescope, the TMT.Access to the TMTwill no doubt enable Indian astronomers to do cutting edge science comparable to their peers elsewhere. However, the gap between the current largest telescope (3.6-meter) and the 30-meter telescope is huge. A 10-meter class telescope in the country is essential to effectively utilise India's share of observing nights with the TMT. Additionally, combined with other large facilities in the country (existing and proposed) such as the GMRT, LIGO-India and space astronomy missions, a 10-meter optical-IR facility in countrywill enablemulti-messenger, multi-wavelength astronomy that will be globally competitive.