Milestone-Proposal talk:The Giant Metrewave Radio Telescope (GMRT) – Pune, India

Review and support by Dr. Jacob Baars -- Juan Carlos (talk) 11:45, 31 July 2020 (UTC)

I am happy to fully support this initiative. I consider myself capable in this matter, having spent most of my career closely attached to radio telescope projects at a leading level. I was assistant project manager for the Westerbork Synthesis Radio Telescope in the Netherlands around 1970. Upon joining the Max-Planck-Institut für Radioastronomie in Bonn, Germany, I was Project Manager of the IRAM 30-m Millimeter Telescope in Spain (19180s) and the Heinrich Hertz Sub-millimeter Telescope in Arizona (1990s). After these projects I was Project Engineer for the Large Millimeter Telescope in Mexico during the design phase and I acted in several senior functions in the ALMA Project as ESO representative.

I have read the GMRT proposal that was attached to your message. It paints a good and complete picture of the project from the initial scientific justification and technical layout to the realization of the hardware in a remarkable indigenous concentration. I support it fully.

I would like to stress one aspect that for me is the most impressive achievement of the project. With the Ooty Telescope the Indian group of radio astronomers had already shown the capability to design and build instruments for a specific scientific purpose. When they considered how to realize a more powerful radio telescope, they recognized that concentrating on a low frequency instrument was not only astronomically highly relevant, because of the lack of such instruments world-wide, but also a viable avenue towards designing and building economically acceptable antenna structures. In short: they needed to build something big for a rock-bottom cost. The resulting design of the original SMART (Stretched Mesh Attached to Rope Trusses) telescope satisfied their goals: a high quality antenna, locally designed and constructed for an affordable low price.

With the GMRT India joined the "high technology" nations with an example of high performance technology, fully developed in the country, providing the science of astronomy with significant observational extension.

Jacob Baars, Member of the Historical Radio Astronomy working group of the IAU (Intl. Astronomical Union)

co-author of Book: “Radio Telescope Reflectors - Historical Development of Design and Construction” , 2017

Review and support by Prof. Richard Schilizzi, Chair of the IAU working group on History of Radioastronomy -- Juan Carlos (talk) 14:59, 2 August 2020 (UTC)

Giant Metre-wave Radio Telescope – IEEE Milestone Proposal

India was one of five countries around the world that pioneered radio telescopes at metre wavelengths in the years since WWII, the others being Australia, Italy, the USA and the USSR (Russia and Ukraine). The Netherlands has followed in the last two decades. In India, this pioneering work was driven by Professor Govind Swarup, one of the major figures in global radio astronomy. His first telescope was the Ooty Radio Telescope (ORT), a cylindrical paraboloid 530m long by 30 m wide (collecting area ~16,000 m2), operating at 327 MHz and completed in 1970. After years of successful work with ORT during which the radio astronomy community built up substantially in India, Swarup led an international African-Indian proposal in 1978 for a large array of parabolic cylinders with collecting area ten times that of the ORT (~200000 m2). This was to be located on the equator in Africa and called the Giant Equatorial Radio Telescope (GERT). However, by the end of 1983, it was clear that GERT would not be funded and Swarup turned his attention to a concept for a new national telescope in India called the GMRT. This was no longer based on cylinders but on the more flexible dishes that allow the telescope to be directed to any point in the sky.

Its design encompasses a number of innovations, one of which, the SMART antenna, was considered for the Square Kilometre Array (SKA) at an early stage. In the end, the SKA choice went to a much more expensive antenna design driven by a scientific requirement to observe at a much higher frequency limit than was possible with the SMART concept.

Since being declared an international facility in 2001, the GMRT, with its ~50,000 m2 collecting area, has been recognised as the most sensitive fully-steerable low frequency telescope in the world, supported by a world-class scientific and engineering staff. It is a multi-purpose Observatory attracting observing proposals from around the world on most of the important topics in astronomy and astrophysics. It showcases Indian achievements and innovation on the scientific and engineering fronts, and has been instrumental in educating many young students who have gone on to careers in astronomy at the most prestigious institutes and universities in the world. The experience accumulated over the years allowed the Observatory to take on leadership of the Telescope Manager design package for the SKA, a significant recognition in itself.

All this has been made possible by the GMRT. It is a significant technical achievement and worthy of an IEEE Milestone Award for its innovation and value for humanity.

Richard T. Schilizzi |Emeritus Professor of Astrophysics Department of Physics and Astronomy | School of Natural Sciences | The University of Manchester Chair of the IAU working group on History of Radioastronomy

Approval by Advocate -- Juan Carlos (talk) 18:47, 2 August 2020 (UTC)

Advocate’s report

The GMRT nomination really deserves to be approved as an IEEE Milestone. As Advocate, I fully endorse it. I’ve received only positive comments, some of them constructive- from IEEE members in the MTT and AP societies, -some of those comments lead to adjustments in the citation- But none of those persons volunteered to offer a complete expert evaluation. I’ve also had positive comments from Members of the History Committee of the American Astronomy Association, but none of the contacted had the time or felt like making an evaluation. Many mentioned the unique metric Microwave window that GMRT provided to their work in extra-galactic supernovae and pulsars observations, resulting in a significant improvement of our knowledge of the Universe. And that the observatory had also provided a unique access to a greater part of the southern celestial hemisphere. They also contributed to the clarification of dates related to the project (see below) On this discussion site I have reproduced positive and enthusiastic evaluations by two members of the International Astronomy Association’s Committee on the History of Radio Astronomy, from Germany and Great Britain. The independent expert evaluations condition is met.

We may have a borderline case in relation to the 25 years condition. The first records of observation (a telescope “first light” ) with the first antenna are dated 1994. But the real value of this telescope comes from observations profiting from the plurality of antennas and their correlation. That started to come later. In 1995 there were a few published papers about the early observations with GMRT, from 1999 onwards there were a lot, indicating the full power of the instrument.

In case of hydroelectric Projects, all the Citations and records refer to the date of the first generation, although the real usefulness of the project, the benefit to the humanity may have been many years later, when the lake is full and all the generators were finished and the full generation capacity of all the units was achieved. New features and renovations keep happening for decades.

We have a similar case here; it’s an excellent project, fully endorsed by prorninent scientists and in my opinion we can and should approve the milestone right now. The present form of the Citation was adjusted with the proposers after a teleconference with Robert Colburn to detail part of the technological significance of the achievement My suggestion for the dates in the tittle would be 1994-1999

Re: Approval by Advocate -- Jason.k.hui (talk) 16:06, 4 October 2020 (UTC)

Given the last sentence, when will the title of the proposed milestone have the updated dates? Also, will the input for the range of years in which the achievement occurred be updated as well? I like Amy's proposed citation revision (noted below).

possible citation editing -- Amy Bix (talk) 14:02, 30 September 2020 (UTC)

neat project! I'm not sure the current citation does it justice, though - the current last sentence, "It has produced several front-line results in a diverse range of topics, greatly enhancing our understanding of the Universe." is particularly vague. Could I suggest some rewriting to make the significance of this project more clear? - maybe something such as:

India pioneered the 1990s revival of low-frequency radio astronomy with its GMRT system of thirty antennas stretching across 25 kilometers, one of the world's most sensitive 110–1460 MHz telescopes. Locally-designed innovations included new techniques in antenna development, digital signal processing, and optical fibers. GMRT-based research produced important discoveries regarding the sun, pulsars, galaxy development, and cosmology, while advancing scientific technology and professional astronomy in India.

Re: possible citation editing -- John Vardalas (talk) 21:03, 30 September 2020 (UTC)

I concur. Elaborating on its significance would better help the reader situate the impact of the achievement.

Re: Re: possible citation editing -- Harish (talk) 12:55, 6 October 2020 (UTC)

Replace this text with your reply

GMRT consisting of 30 antennas of 45m diameter each, stretching across 25 kilometres near Pune, India, is one of the largest and most sensitive low frequency (110–1460 MHz) radio telescopes in the world. It pioneered new techniques in antenna, RF design, optical fibre for signal transport and signal processing. GMRT has produced important discoveries in domains such as Pulsars, Supernovae, Galaxies, Quasars, and Cosmology, greatly enhancing our understanding of the Universe.

Re: Re: Re: possible citation editing -- Harish (talk) 16:07, 6 October 2020 (UTC)

Replace this text with your reply

The Giant Metrewave Radio Telescope (GMRT) -1993

GMRT consisting of 30 antennas of 45m diameter each, stretching across 25 kilometres near Pune, India, is one of the largest and most sensitive low frequency (110–1460 MHz) radio telescopes in the world. It pioneered new techniques in antenna design, RF, Optical fibre for signal transport and Signal processing. GMRT has produced important discoveries in domains such as Pulsars, Supernovae, Galaxies, Quasars, and Cosmology hence greatly enhancing our understanding of the Universe.

Noted for History Committee consideration -- Djkemp (talk) 21:41, 2 October 2020 (UTC)

Noted

Re: Noted for History Committee consideration -- Jbart64 (talk) 00:16, 7 October 2020 (UTC)

I support the milestone with a minor edit: delete the word "hence". Dave Bart

=== Comments Posted on behalf of Dubner by Administrator4

I am writing in support of the proposal to honor the Giant Metrewave Telescope (GMRT) with the IEEE Milestone recognition. Until recently I have been the director of the Institute of Astronomy and Space Physics in Buenos Aires (IAFE- University of Buenos Aires and Argentina National Council of Sci. & Tech. Research) and Head of the group “Supernova Remnants and the Interstellar Medium” in IAFE. Along my career my main interest has been the investigation of the aftermath of stellar explosions, mostly based on observations in the radio band of the spectrum. To carry out my research I have used the most powerful radio telescopes in the world, including the VLA (USA), ATCA (Australia), ALMA (Chile), eEVN (the European network of radio telescopes) and GMRT (India). The radio waves provide a very wide window to explore the universe, five decades in frequencies, from sub-millimetric to decametric waves. This makes radio telescopes one of the prime tools to explore the sky from Earth, since they permit the investigation of a large variety of physical phenomena in the universe. However, as the spatial resolution of a telescope is proportional to its operating frequency, telescopes working at low radio frequencies produce “blurred” images, thousands of times worst resolved in comparison with optical pictures of the sky. This discouraging aspect, together with the disturbing effects that the ionosphere has on the observations in this spectral range (irregularities in the ionosphere reflect in radio images just like the atmosphere causes stars to twinkle), had the consequence that for many years the low-frequencies extreme of the spectrum was neglected (although radio astronomy was born in 1931 precisely in these frequencies). Yet several very important astrophysical phenomena, including supernova remnants, pulsars, energetic processes at the center of the galaxies, and the relic radiation from the dawn of the universe (the epoch of reionization, when the first stars formed and their light ionized the matter) demand observations precisely at low radio-frequencies to be discovered and studied. One way to overcome the low spatial resolution problem is by combining the signals of several antennae in an array, operating like a big interferometer, and it has to be installed in a site with minimum ionosphere problems. Here is where the whole idea of constructing the GMRT came as an excellent solution. By conceiving a radio telescope consisting of an array of 30 antennae, each of 45 m diameter, spread over a region of 25 km diameter, the instrument achieves high-angular resolution (at the time it was built, it was the world's largest interferometric array) and the choice of the site in India was very adequate because, in addition to low man-made radio noise, it is at a geographical latitude sufficiently north of the geomagnetic equator in order to have a reasonably quiet ionosphere and yet be able to observe a good part of the southern sky as well. This last aspect, together with the experience of Indian scientists and engineers on low-radio-frequencies gained with the Ooty radio telescope, gave to GMRT a special advantage during many years. It was the only radio telescope operating at low frequencies capable to observe all the northern sky and the south down to declination of -59 degrees. In the year 1999, when the telescope opened to users from all over the world, it was organized the symposium “The Universe at Low Radio Frequencies: All Aspects of Radio Astronomy below ≈1 GHz”, sponsored by the International Astronomical Union, in which I had the privilege of being invited to deliver a talk on supernova remnants. In that occasion I made my first visit to the observatory, and I remember that a frequent comment among the participants was the admiration of the design of the antennae, that we called “the mosquitoes” because of the figure of the very light, almost empty antennae made of thin stainless steel wire ropes, the very ingenious SMART (Stretch Mesh Attached to Rope Trusses) concept. Such design was definitively a breakthrough. From that trip I also remember meeting several female engineers involved in different aspects of the project. After then, me and my graduate students conducted several observations with GMRT to investigate pulsars , supernova remnants and searching for radio sources that may help to understand the nature of the “dark” sources discovered by their emission in gamma-rays, the most energetic extreme of the electromagnetic spectrum. Undoubtedly, the GMRT has been one of the most challenging experimental programs in radio astronomy that came to solve the lack of sensitive, high-angular resolution, instrument operating in the lowest extreme of the spectrum, with the possibility of reaching a good part of the southern sky. Nowadays there are other high-quality instruments operating in the same spectral range and covering the southern sky, like the new Murchison Widefield Array (MWA) in Australia and others in the north (Lofar, LWA, etc), but the GMRT continues at the front line producing important contributions to our knowledge of the universe.

Gloria Dubner Senior Researcher of the National Council of Scientific and Technological Research of Argentina (CONICET) Vice president of the National Academy of Exact, Physical and Natural Sciences Member of the International Astronomical Union