University of Calcutta

INSTITUTE OF RADIO PHYSICS AND ELECTRONICS (IRPE)

UGC NETWORKING RESOURCE CENTRE IN PHYSICAL SCIENCES

One day Seminar: M.K.Dasgupta Memorial Seminar (International Year of Astronomy)
September 1, 2009

About The School

The Institute of Radio Physics and Electronics, University of Calcutta, the first University Department in India to conduct post-graduate teaching program in Electronics, Communication, Computers and Radio Science organized a one day seminar in memory of late Professor Mrinal Kumar DasGupta, the doyen of radio astronomy in India, on his birthday, September 1, 2009 as part of its Golden Jubilee celebrations and the International Year of Astronomy. This seminar was planned in accordance with the suggestion of Prof. N.K. Dadhich, UGC nominated expert in the CAS Advisory Committee in the Department. The seminar was held under the auspices of the UGC Networking Resource Center, a distinction earned by the Institute in 2008. This Institute has a long tradition of research in the area of Space Sciences and Astronomy with late Professor Sisir Kumar Mitra being the pioneer. Professor Dasgupta, a Faculty of this Institute from 1954-1988, made pioneering contributions in radio astronomy along with his co-researcher Roger Jennison of Jodrell Bank Observatory. They were the first to design, fabricate and successfully operate a radio intensity interferometer. Dasgupta and Jennison found the first evidence of a “radio galaxy” which was a galaxy with two radio emitting lobes on both sides of it with a separation of a few hundred light years, on two strong radio sources – Cygnus A and Cassiopeia A. This discovery of the double radio source in Cygnus A by Dasgupta and Jennison in 1953 is now regarded as one of the ten classical discoveries in radio astronomy.

The seminar was originally planned with five invited speakers, namely, Professor Govind Swarup, Ex-Director, Giant Meterwave Radio Telescope (GMRT), Professor S. Ananthakrishnan, Ex-Observatory Director, Giant Meterwave Radio Telescope (GMRT) and presently associated with Pune University, Dr. Rajaram Nityananda, National Center for Radio Astrophysics (NCRA), Professor Ashok Ambastha, Udaipur Solar Observatory and Professor N. Udaya Shankar, Raman Research Institute. However, Professor Swarup could not attend the meeting because of health problems. The detailed program of the seminar is enclosed with this report.

The seminar started with the welcome address being delivered by Prof. G. Ghosh, the then Head of the Department. Prof. Ghosh spoke about the glorious history of the Department which had made significant contributions in areas related to Upper Atmospheric studies. The next speaker was Prof. S. Sen, the then Dean of the Faculty of Engineering and Technology who spoke about existing collaborations of the University with centres like National Centre for Radio Astrophysics (NCRA) and Indian Institute of Astrophysics (IIA) for teaching as well as research in different areas of radio astronomy. The Presidential address was delivered by Prof. P.K. Basu, Director, UGC Networking Resource Centre in Physical Sciences who briefed the participants about the various activities of the Centre. Dr. A. Paul, Convenor of the seminar presented the vote of thanks.

The inaugural session was followed by Reminiscences where family members of Prof. DasGupta, namely his wife, son and daughter-in-law spoke about different aspects of his towering personality and recited some of his poems which revealed an unknown façade of his character. Prof. P. Bandyopadhyay and Prof. A. DasGupta, retired teachers of the Institute of Radio Physics and Electronics spoke effusively on the pioneering contributions of Prof. DasGupta towards Space Science in India. A message from Dr. Santimay Basu, Senior Research Physicist, Boston College, USA who was Prof. M.K. DasGupta’s first graduate student was read out by Dr. A. Paul. It contained several anecdotes of memories of working with Prof. DasGupta on solar radio astronomy that have not faded despite the intervening decades. Dr. D.P. Duari, Director, Research and Academics, M.P. Birla Institute of Fundamental Research shared his early interactions with Prof. DasGupta as an examiner. Prof. Amalendu Bandyopadhyay of the same Institute recalled his experience of working in close quarters with Prof. DasGupta during his last days. The session was chaired by Prof. P.K. Basu.

The first speaker in the pre-lunch technical session was Prof. S. Ananthakrishnan who was the Observatory Director of the Giant Meterwave Radio Telescope (GMRT) and is presently associated with the Electronic Science Department of Pune University. Prof. Ananthakrishnan traced the evolution of radio interferometry including Very Long Baseline Interferometry (VLBI) techniques and also described a recent proposal that aims to locate two triaxial radio antennas, one each on a lunar orbiter and a lunar rover respectively. Such an experiment will form a simple interferometer with a few hundred to a few thousand kilometre baseline using the VLBI technique and will provide a unique new window to the low frequency Universe from the Moon, between 1 MHz to 20 MHz which is inaccessible from the Earth.

The next speaker was Prof. Rajaram Nityananda, Director, National Centre for Radio Astrophysics (NCRA) who spoke about the key ideas which have driven the imaging of radio emission from the universe by astronomers, in which Prof. Dasgupta’s work with Jennison was an early breakthrough. He reviewed the current capabilities and critical issues with emphasis on the low frequencies at which the GMRT, located in Khodad, near Pune, represents some of the best current capability in the world.

The post-lunch technical session started with the talk by Prof. Ashok Ambastha, Udaipur Solar Observatory who spoke about helio- and coronal seismology. The solar interior is not visible by direct means, and until a few decades back its understanding was based only on the surface observations coupled with theoretical models. Helioseismology which uses global solar oscillations, trapped in the solar interior, has provided a tool to probe the Sun’s internal structure and dynamics. Coronal seismology, on the other hand, exploits the coronal waves and oscillations as a diagnostic tool for determining the physical conditions of the magnetized coronal plasma. MHD wave theory forms the basis for coronal seismology. While the helioseismic techniques have reached a fairly advanced stage, they are predominantly based on purely hydrodynamical models. He commented that in the coming years, the inclusion of magnetic effects in the local helioseismic techniques is likely to become an important issue.

The final speaker of the day was Prof. N. Udaya Shankara from Raman Research Institute. He said that early radio observations were severely limited both by the poor angular resolution and by the limited sensitivity. It was usually impossible to obtain any information about the structure of a source, and adjacent sources could often not be properly separated. This motivated Martin Ryle, Nobel Laureate in 1974, and his colleagues to develop the method of aperture synthesis which in the early days helped to avoid the severe structural problems of building very large and accurate paraboloids and allowed both high resolving power and large effective collecting area to be obtained with a minimum of engineering structure and therefore cost. In this lecture he discussed dipolar arrays, a version of modern Michelson Stellar interferometers, in which beam-forming networks are used to combine signals from antenna elements. Quasi-optical antennas such as parabolic reflectors are considered more appropriate for milli-meter and centi-meter wavelengths. At the other end of the radio spectrum, for meter and deca-meter wavelengths, multi element arrays of dipole antennas have been preferred. The seminar was attended by Faculty Members, Research Scholars and some B.Tech. and M.Tech. students of the Institute of Radio Physics and Electronics and S.K. Mitra Center for Research in Space Environment, Department of Electronic Science, Department of Statistics, Department of Applied Optics and Photonics, Bose Institute, Indian Institute of Science Education and Research, St. Xavier’s College, Raja Peary Mohan College, M.P. Birla Institute of Fundamental Research, Jadavpur University, Burdwan University and some private engineering colleges like Academy of Technology and Institute of Technical and Marine Engineering. A list of the participants is enclosed.

Photos

Selection of Candidates

The submitted registration forms were examined and a list of selected fellows was published in the website to enable them to reserve train/air tickets. Due consideration was given to select participants from all over India and to give preference to candidates from North Eastern regions. The following Table may provide an idea how the objective was fulfilled.