A tribute to Professor Govind Swarup, FRS: the Father of Indian Radio Astronomy

In this paper we pay a tribute to the 'Father of Indian Radio Astronomy', Professor Govind Swarup, BSc, MSc, PhD, FRS, by celebrating his 90th Birthday (which occurred on 23 March 2019) and recounting his remarkable scientific achievements in three disparate regions of the globe: the Indian Subcontinent, Australia and the United States of America. Between 1953 and 1955 Govind served what was effectively an 'apprenticeship' in radio astronomy while on a Colombo Plan Fellowship at the Commonwealth Scientific and Industrial Research Organisation's Division of Radiophysics in Sydney, Australia. After a short time back in India, he moved to Harvard University's Fort Davis Radio Astronomy field station in Texas, USA, and one year later, in September 1957, began a PhD in radio astronomy under the guidance of Professor Ron Bracewell at Stanford University. Soon after completing his doctorate and accepting a faculty position at Stanford, Govind and Bina Swarup returned to India so that Govind could launch a radio astronomy program at the Tata Institute of Fundamental Research in what was then still known as Bombay (present-day Mumbai). In 1963 this led to the construction at Kalyan, near Bombay, of India's first radio telescope, an array of 32 six-feet (1.8-m) diameter parabolic dishes that served as a 610 MHz solar grating interferometer. This innovative T-shaped radio telescope was a rebadged version of the 1420 MHz East-West solar grating array that was designed by Dr W.N. (Chris) Christiansen and erected at the Potts Hill field station in Sydney in 1952. But it had a special place in Govind's heart because back in 1955 he and fellow Colombo Plan student, R. Parthasarathy, had reconfigured this as a 500 MHz grating array and used it to search for evidence of solar limb brightening. Govind's next radio telescope was a solely Indian affair and an ingenious concept that took full advantage of southern India's geographical location near the Equator. The Ooty Radio Telescope was built between 1965 and 1970 and comprised a N-S oriented 530-m x 30-m parabolic cylinder that was located on a hill with the same slope as the latitude of the site, i.e. 11 degrees. This de facto 'equatorial mounting' meant that radio sources could be tracked continuously for 9.5 hours every day. The Ooty Radio Telescope was used mainly to measure the positions and angular sizes of faint radio galaxies and quasars. After abortive attempts to erect a Giant Equatorial Radio Telescope (GERT) of similar design, first in Kenya and then in Indonesia, in 1984 Govind conceived the idea of constructing a low frequency synthesis radio telescope in India. During the 1990s this emerged as the Giant Metrewave Radio Telescope (GMRT) near Pune, an array of 30 45-m diameter fully-steerable parabolic dishes that has been used over the past two decades by Indian and overseas radio astronomers to investigate a variety of discrete sources at decimetre and metre wavelengths. In March 2019 the National Centre for Radioastrophysics, held an international conference in Pune to celebrate Govind's 90th Birthday and the recent major upgrade of the GMRT. Govind, you truly are the 'Father of Indian Radio Astronomy', and with affection and profound admiration for all that you have achieved in a lifetime devoted to radio astronomy we offer you this paper as an additional - if slightly belated - birthday present.