Nuclear India (May-Jun 2004)

GMRT Discovers a Unique Pulsar

Setup at Narayangaon near Pune, Maharashtra, the Giant Metrewave Radio Telescope (GMRT) comprising 30 fully steerable antennas each of 45m diameter and spread over an area of 25km in a Y-shaped array, is the world's largest radio telescope in the metre wavelength region.

GMRT has emerged as an international facility for research in astronomy. A recent success of GMRT includes discovery of a binary pulsar.

A team with members from National Centre for Radio Astronomy (NCRA)-TIFR, the Arecibo Observatory in Puerto and McGill University in Canada, using GMRT has discovered a "binary millisecond pulsar". A pulsar is an incredibly small and hence, dense star, heavier than the Sun, but a hundred thousand times smaller, spinning rapidly and emitting radio waves. It takes near super-computing power to detect the very weak pulse in the data, but GMRT, due to its high sensitivity, has an inherent advantage in such observations.

The Giant Metrewave Radio Telescope (GMRT) consists of 30 fully steerable antennas each of 45m diameter. The antennas are spread over an area of 25km in a Y-shaped array. GMRT is the world's largest radio telescope in the metre wavelength region.

A team with members from National Centre for Radio Astronomy (NCRA)-TIFR, the Arecibo Observatory in Puerto and McGill University in Canada, using GMRT has discovered a "binary millisecond pulsar". A pulsar is an incredibly small and hence, dense star, heavier than the Sun, but a hundred thousand times smaller, spinning rapidly and emitting radio waves. This particular pulser was looked for and found near the centre of a star cluster known as NGC 1851. It takes near super-computing power to detect the very weak pulse in the data, but GMRT, due to its high sensitivity, has an inherent advantage in such observations.

A few dozen such orbiting pulsars are known, but this one has the most elongated orbit. The precise location was pinned down by using the GMRT's capability of making a "picture" with radiowaves, by combining signals from thirty antennas in a region 20km in size.

Apart from studying pulsars, GMRT is used for studying a variety of objects ranging from the Sun to far away clouds of hydrogen from which galaxies may have formed in the distant past, billions of years ago. The current discovery is a visible tribute to the sophisticated engineering, hardware and software which have gone into setting up of this telescope which the Tata Institute of Fundamental Research embarked on in the late nineteen eighties, setting up National Centre for Radio Astronomy in the process.

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