A Global Prospective of the Indian Optical and Near-Infrared Observational Facilities in the Field of Astronomy and Astrophysics: A Review

Abstract

A review of modernization and growth of ground based optical and near-infrared astrophysical observational facilities in the globe attributed to the recent technological developments in opto-mechanical, electronics and computer science areas is presented. Hubble Space Telescope (HST) and speckle and adaptive ground based imaging have obtained images better than 0.1 arc sec angular resolution bringing the celestial objects closer to us at least by a factor of 10 during the last two decades. From the light gathering point of view, building of large size (> 5meter aperture) ground based optical and near-infrared telescopes based on latest technology have become economical in recent years. Consequently, in the world, a few 8-10 meter size ground-based optical and near-infrared telescopes are being used for observations of the celestial objects, three 25-40 meter size are under design stage and making of a ~ 100 meter size telescope is under planning stage. In India, the largest sized optical and near-infrared telescope is the modern 3.6-meter located at Devasthal, Nainital. However, the existing Indian moderate size telescopes equipped with modern backend instruments have global importance due to their geographical location. Recently, the Government of India approved India's participation in the Thirty Meter Telescope (TMT) project.

Scientific potential of the Indo-Belgian 3.6-m DOT in the field of Galactic Astronomy

“…Also, it has number of FUV and NUV filters in comparison to other recent similar space missions. UVIT images, in combination with other space and ground based data, are a very powerful tool to understand the formation of UV and blue stellar population in star clusters (see Sahu et al 2019and Subramaniam et al 2016, 2017. However, for proper understanding of their progenitors, extensive photometric and spectroscopic studies at optical and NIR wavelengths are essential.…”

“…The 3.6-m DOT was used for detailed characterisation of these instruments as well as for some science programs, which included photometric and spectroscopic study of supernovae, optical transient events, AGNs and quasars, galactic star forming regions, and distant galaxies. Omar et al (2017) and Sagar (2017) have highlighted scientific potential of the 3.6-m DOT. The key results of the sky quantification are briefly summarised in the ensuing sub-sections.…”

The 3.6 meter Devasthal Optical Telescope: From inception to realisation

“…6 Highlights of recent results from the 3.6m DOT After successful installation and performance verification, the technical activation of the 3.6-m DOT was done jointly by both Indian and Belgian premiers on March 30, 2016 from Brussels, Belgium. Scientific potential and capabilities of the telescope are published elsewhere 1,41,42 . Observing proposals from the users are submitted online twice in a year for both observing cycles namely Cycle-A (February to May) and Cycle-B (October to January).…”

“…These optical telescopes are primarily used for photometric and low-resolution (∼ 2000) spectroscopic studies of relatively brighter celestial sources (V ≤ 21 mag). Their global relevance in the era of multi-wavelength astronomy have been highlighted elsewhere 1 . The large size optical telescopes help in probing fainter and distant celestial sources.…”

Scientific Capabilities and Advantages of the 3.6 Meter Optical Telescope at Devasthal, Uttarakhand

“…Other major optical telescopes in the country have diameters between ~1 and 2 m (ref. 2). The Indian astronomers planned to install a modern 4-m class optical telescope in the country many years ago.…”