Govind Swarup, a distinguished Indian radio astronomer, passed away on September 7, 2020, in Pune (India), at the age of 91. He was a member of the Pontifical Academy of Sciences since 2008. A brilliant experimentalist, working on radio emissions from the Sun and galaxies, he played a decisive role in the early developments of radio-astronomy in India, leading to the conception and construction of a world-class facility, the Giant Meterwave Radio Telescope near Pune. He established an outstanding science group at Tata Institute for Fundamental Research (Mumbai), where he spent all his career.
Born in 1929 in Thakurdwara (today in Harit Pradesh), a city 150 km East of New Delhi, he studied physics at Allahabad where he graduated in 1950, then he spent the decade first staying at the National Physical Laboratory in Delhi, then becoming Research associate at Harvard and Stanford University, where he got his PhD in 1961 under the direction of the famous radio astronomer Ronald Bracewell.
After two years as Associate Professor at Stanford, returning in 1963 to India he spent two years at the National Physical Laboratory in Delhi, before being called by Homi Bhabha, the founder and first director, to join Tata Institute for Fundamental Research (TIFR) created in June 1945 in Mumbai as one of the leading scientific laboratories of India. There, in 1965 he became Associate Professor, Professor in 1970, and Professor of Eminence in 1989. He was elected Project Director of the GMRT in 1987 and Centre Director of the National Center for Radio Astrophysics (NCRA) of TIFR in 1993. He retired from TIFR in 1994.
Radio astronomy was born in 1933 (first observations by Karl Jansky) and developed rapidly after World War 2, thanks to the technical developments made on radar and electronics. This opening field offered a great potential for discoveries to a young scientist. Govid Swarup first studied the Sun, both in its radio-quiet state and in its bursting phases, which impact radio transmissions on Earth. His experimental talents soon led to a round trip transmission technique for phase measurements, then used in almost all the radio interferometers in the world. The increasing sensitivity of radio telescope interferometers allowed him in 1962 to discover the first example of a bridge of radio emission between the two lobes of the radio galaxy Cygnus-A, hence estimating its age.
During the 1960s, he undertook to give India an innovative radio telescope, at Ooty (Tamil Nadu, South India). Taking advantage of lunar occultations, which provided a high spatial accuracy of 1 to 10 arcseconds, he measured the positions of more than 1,000 radio sources. These measurements provided an independent support for the Big-Bang standard model of cosmology. Worth mentioning here is one of the first measurements of the source SgrA*, where he separated the thermal and non-thermal emissions. In the years 2000, this source would turn out to be a supermassive black hole in the Galaxy.
Time was ripe for a more ambitious project, the Giant Metrewave Radio Telescope (GMRT), which he conceived. He then directed the design and construction from 1984 to 1996, developing a low-cost concept for the antennas. GMRT, made of 30 fully steerable parabolic dishes of 45 m diameter, is an interferometric array extending over 25 km near Pune and is the world’s largest radio telescope operating in the frequency range 130-1430 MHz (wavelengths in the meter range). Using himself this instrument, he observed the emission and absorption of atomic hydrogen from objects in the early Universe. Along with S.K. Sirothia, he investigated deficiency of radio sources at 327 MHz towards the prominent ‘cold’ spot of the cosmic microwave background radiation.
To summarize, he made important contributions in areas such as solar radio emission, interplanetary scintillations, pulsars, radio-galaxies and cosmology. He published over 125 research papers and edited 4 books. He had two patents.
Govid Swarup was a leading national and international figure, as shown by his numerous affiliations and roles. He was member of the Royal Society and the Royal Astronomical Society (London), of the Third World Academy of Sciences (TWAS), President of the International Astronomical Union (IAU) Commission on Radio Astronomy, member of the National Academy of Sciences of India, and several other Indian Academies. He received many distinctions, culminating in 2007 with the Grote Reber Medal, the Indian Science Congress Association Medal and in 2009 the Homi Bhabha Award.
We remember the last long contribution he made during our 2008 Plenary Session, while speaking on the ‘Scientific quest into the evolution of life in the universe’ and discussing this issue with his charming smile. Then, after a broad summary of astronomical knowledge on universe and recently discovered exoplanets, he as radio-astronomer naturally discussed the issue of intelligent life in the universe, to be possibly detected by SETI methods (Search for Extraterrestrial Intelligence). He concluded with an interrogative quote from the Rig Veda, and a hopeful statement in human beings, saying: “I think our humanity on this Earth is not going to disappear in hundredths of years. But […] in the future, how to make sure that we protect our environment, so that we will live for a long time”.