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Radio Infra-red Optical Optical/NIR
interferometry
Ultra-violet X-ray Γ-ray

Giant Meterwave Radio Telescope (GMRT)

Photo courtesy of R. Subrahmanyan

The GMRT, located near Pune in India, is the youngest of the current large interferometers. It consists of 30 45-m antennae and operates at wavelengths from 4 m (75 MHz frequency) to 20 cm (1.5 GHz). This makes it possible to use as the antenna surfaces a wiremesh, which makes them look translucent.

Another strength of the GMRT is its location quite close to the equator, due to which is can observe both the northern and the southern sky, missing only quite small areas in the polar regions. Why is this important? Well, although radio waves can penetrate whole galaxies (meaning, pass through the gas in these), we have not devised ways or means yet to observe through the Earth... So some parts of the sky will always remain below the horizon, even for radio astronomers.

Operating at low radio frequencies, the GMRT's major strengths lie in observations of nonthermal radio continuum emission and of the HI line of neutral Hydrogen.