Abstract


  A GLOBAL PERSPECTIVE OF OPTICAL TELESCOPES IN INDIA

  R. Sagar, Indian Institute of Astrophysics, Bangalore, ram_sagar0@yahoo.co.in

It is well known that the ancient Greeks and Romans gazed at the night skies while traveling on the high seas and drew their own conclusions about the stars which were visible to them. However, it was not until the invention of the first telescope that study of heavens began on a scientific footing. An optical telescope is used to image celestial objects at its focus just like our Eye images the objects on our retina. However, telescopes with larger aperture sizes collect more photons and also provide better angular resolutions than the eye. With the advancement of technology, larger and larger telescopes were constructed to probe deep into the space. Recent developments in electronics, computer and in other areas of technology have contributed significantly to the growth of optical telescopes, detector and analyzer. From the angular resolution point of view, launch of 2.3 meter Hubble Space telescope and Speckle interferometry and adaptive optics ground based imaging have been able to obtain images better than 0.1 arc sec angular resolution. Thus Universe has been brought closer to us at least by a factor of 10 during last two decades or so. Similarly from the light gathering point of view building of large size optical telescopes based on latest technology have become economical in recent years. Consequently, largest size optical telescope being used for observations of the Universe is 16 meter, a few of more than 25 meter size are under design stage and making of about 100 meter size optical telescope is under planning stage. One can thus say that recent developments during the last few decades have revolutionized optical Astronomy. In India, however, the largest optical telescopes of 3.6-meter thin mirror active support modern and 4-meter international liquid mirror sizes are under installation at Devasthal, Nainital. It is based on new technology and has both national and international participation. Such Indian observational facilities have global importance due to its geographical location. These along with road map for the growth of Astrophysical observational facilities will be described during the presentation.