Come 2018, upgraded GMRT will open new windows on the universe

"About 75-80 per cent of the upgradation of the existing electronics and systems of the GMRT has been completed."

Written by ANJALI MARAR | Narayangaon /pune | Published:May 29, 2017 4:12 am
gmrt, gmrt line, gmrt high frequency, maharashtra gmrt, shivneri gmrt, lenyadri gmrt, indian express One of the 13 antennas in the centre square area of GMRT. Sandeep Daundkar

Apart from being popular tourist places in Maharashtra, Shivneri and Lenyadri are the two main computers in the control room of the Giant Metrewave Radio Telescope (GMRT) and will soon oversee into a new age in the exploration of the universe, with the observatory entering its last phase of its upgradation to a next generation facility.

Once the upgrade is completed, this observatory, presently the world’s largest astronomy telescope operating at low radio frequencies, will have enhanced capabilities which will remain unmatched till the Square Kilometre Array (SKA), the proposed largest radio telescope in the world, comes into existence by around 2023 or so.

“About 75-80 per cent of the upgradation of the existing electronics and systems of the GMRT has been completed. Some of the new systems have already been put into operations for undertaking research and the first science results have started coming in,” stated Yashwant Gupta, dean of the GMRT observatory.

GMRT is an array of 30 antennas, spread across a 30-km diameter region centered near the village of Khodad in Junnar taluka, about 80 km from Pune. While 13 of these antennas are positioned in the central square of the observatory, an area spanning 1 km by 1 km, the remaining are spread out in 3 arms of about 14-km length in the east, west and south directions in a roughly “Y”-shaped formation.

It is used by astronomers from all over the world and is currently more than twice in demand for its usage than the amount of time available for slotting.

The present day GMRT, which was conceived and designed in the late 1980s and built during the 1990s, suiting the main scientific requirements and technical capabilities at that time, allows astronomers to use it in five limited frequency bands : 150 MHz, 234 MHz, 325 MHz, 610 MHz and 1000 to 1400 MHz, with a maximum bandwidth of 32 MHz.

However, with the upgrade now, engineers and scientists are taking a mighty leap in this frequency range, which will now provide continuous coverage from 120 MHz to 1460 MHz with limited or hardly any gap, along with a maximum bandwidth of 400 MHz, which scientists say, is more than 10 times larger than that of the original GMRT system.

In other words, two main improvements brought about in GMRT would mean that here on, it would be possible to receive radio signals from far-off celestial objects at a wider range of distances in the universe; secondly, it would detect much fainter and newer objects, thereby offering a deeper spectrum of study for the astronomy community.

With an increase in traffic of the incoming signals due to the improved electronics, scientists also identified the need to scale up the carrier, storage and computing capacities of the observatory. What is to be noted is that, even while undertaking upgradation works, scientists here are wasting no time, but instead juggling schedules between the old and new systems simultaneously to provide maximum benefits to the user.

“Ensuring a smooth transition, all necessary care is being taken so that there is no obstruction to the ongoing observations, even as newer systems are being developed and tested parallelly,” said Suresh Kumar, incharge of GMRT’s analog receiver system.

While most of the high-tech electronics and computer systems have been scaled up, the last leg of improvements is expected to be completed by the end of 2017.

While “Make in India” may be a term that gained popularity only recently, GMRT team has been silently practising this with its indigenously developed systems for several years now, and the upgrade continues this tradition of in-house development of the technologies.

“Since the needs of the original and upgraded GMRT are highly specialised, we realised that developing our own systems and equipment was the only solution,” said S K Ghosh, NCRA director. The biggest advantage in doing so has not only been keeping the costs in check, but also the ease and availability of in-house maintenance team. “Most of the systems being used in the GMRT have been ideated, designed, developed, fabricated, tested and installed by own team members,” Kumar said.

Local work force has been of immense help to the team, as once the design of any system of the GMRT is approved, it is then mass produced locally as far as possible, as per requirement.

Accurate keeping of time and frequency are two of the most important needs of any observatory, for which the heart of the GMRT is also being upgraded to a hydrogen Maser system, a set up that helps maintain a better standard in time and frequency.

“With this improved facility, we will be able to get 100 times more accurate and stable readings, which will improve the sensitivity of the system, and also allow us to think about developing our own time standard for the observatory in the future,” said Ajith Kumar, incharge of GMRT’s digital system.

“This upgrade in the time and frequency standards will allow the GMRT to carry out Very Long Baseline Interferometer ( VLBI) observations in coordination with other observatories across the world, and also improve the ability to study more accurately exotic neutron stars, also called pulsars,” added Gupta.

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