M. K. DASGUPTA (1923-2005)
Professor Mrinal Kumar Das Gupta was born on 1st September, 1923 in Barishal district of erstwhile
East Pakistan (presently Bangladesh). He got his Bachelor and Master of Science in Physics from
Dhaka University in 1944 and 1945 respectively, where he had the privilege to be taught by Professor
Satyendra Nath Bose of Bose-Einstein statistics fame. M.K. Das Gupta joined the Department of Radio
Physics and Electronics, University of Calcutta, as a researcher under the supervision of the legendary
Professor S.K. Mitra, the pioneer of Radio Research in Asia with the recommendation of Professor S.N.
Bose. As a research assistant to Professor Mitra, Das Gupta successfully set up an instrument for
generation of active nitrogen glow by high-frequency discharge. Professor Mitra was impressed by the
talent, drive and aptitude of his student M.K. Das Gupta and sent him to Manchester University, U.K,
to do further research towards a Ph.D degree under the supervision of Professor P.M.S. Blackett, a
renowned physicist and Nobel Prize winner in 1948. While at Manchester, Das Gupta got the rare
opportunity to work at the Jodrell Bank observatory during 1950 - 1954. He obtained his Ph.D. degree
in 1954 from the University of Manchester. Das Gupta's pioneering contribution along with his coresearcher Roger Jennison of Jodrell Bank Observatory, U.K, was in Radio Astronomy. Astronomical
observations at radio wavelengths (1cm to 10m) created a new branch of astronomy called Radio
Astronomy. Until 1930, knowledge of the universe outside the earth came almost entirely from optical
astronomy observations. The science of Radio Astronomy had its beginning in the experiments on
cosmic radio noise in 1931 by Karl G Jansky, a radio engineer at Holmdel, New Jersey, the field site of
the Bell Telephone Laboratories. However, only after the Second World War the scientific community
took the subject of Radio Astronomy seriously. Nowadays, Radio Astronomy is considered to play a
pivotal role in the exploration of the most distant parts of the universe, where optical astronomy
cannot probe.
Das Gupta and Jennison were the first to design, fabricate and successfully operate the long-base-line,
post-detector correlator radio interferometer, known as the intensity interferometer, which was
conceived by R. Hanbury Brown in 1950. At that point of time, the radio astronomical observations
were limited by poor angular resolution of the radio telescopes and also by the limited sensitivity of
the receiving system. However, with long-base-line intensity interferometer these problems were
expected to be possible to overcome. Using this instrument Das Gupta and Jennison, measured the
apparent angular structure of two strong radio sources - Cygnus A and Cassiopeia A - for the first time
with desired precision. This discovery of the double radio source in Cygnus A by Das Gupta and
Jennison is now regarded as one of the ten classical discoveries in Radio Astronomy. The results of
their land-marking discovery were published in two of the leading and most prestigious journals of the
world: Nature and Philosophical Magazine. The discovery of Das Gupta and Jennison is perhaps the
first indirect evidence for astrophysical black holes, when astronomers were yet to accept the concept
of black hole in the first place! Today, it is known that almost all the radio galaxies and enigmatic
quasars show double structures.
Back to India, during 1955 - 1988, Professor Das Gupta built up an active research school under his
tutelage, first as a teacher and subsequently as the Professor-in-Charge of the Space Science division
of the Center of Advanced Study in Radio Physics and Electronics. In collaboration with his research
students, he made significant research contributions in the fields of Atmospherics, Solar-terrestrial
Physics, Solar Microwave and X-ray emission and in allied topics. After his retirement from university
service in 1988, he served as an INSA Senior Scientist during the period 1988 - 1991. In collaboration
with his student and colleague, Professor A.K.Sen, he successfully conducted a Research Project
entitled "Microwave rain attenuation from radiometric measurements at 12 GHz and 22.235 GHz"
under Indian Middle Atmosphere (IMAP) program funded by the U.G.C.
Professor Das Gupta was intellectually and socially very active till his last days. With his initiative a
diploma course in Astronomy and Planetarium Science, offered by the M.P. Birla Institute of
Fundamental Research, Kolkata, started from 1992, of which he was the course director till his death.
This course is the first of its kind in India.
For his pioneering research in Radio Astronomy, Professor Das Gupta was elected as the Fellow of the
National Academy of Science ( FNA ) in 1974 by the Indian National Science Academy ( INSA ), New
Delhi, and as the Fellow of the Academy of Science ( FASc ) by the Indian Academy of Science,
Bangalore. Professor Das Gupta was felicitated at an international symposium on "Black Holes"
organized by the S.N. Bose National Center for Basic Sciences, Kolkata, in 1998. He was the President
of
the
engineering
section
in
the
68th
Science
Congress
held
at
Benaras
in
1981.
In addition to being a pioneering radio astronomer, Professor Das Gupta was a down-to-earth person
with great compassion and wisdom. He was an avid reader and prolific writer. When we browse
through the pages of popular science magazines one or two decades back, we can find articles on
Radio Astronomy by Professor Das Gupta. He also liked to write Bengali poems in his leisure time. He
used to deliver regular radio talks on popular science and he was also very apt in explaining live solar
and lunar eclipse phenomena in TV programs.
He breathed his last on November 28, 2005 at his residence in Kolkata. He is survived by his wife, a
son and a daughter. He left behind innumerable students, friends and well wishers.