The Upgraded GMRT: Current Status and Plans

The Giant Metrewave Radio Telescope (GMRT), located near Pune in India, is an array of thirty fully steerable parabolic radio telescopes of 45 metre diameter, observing at metre wavelengths. It is the largest and most sensitive radio telescope array in the world at low frequencies, operational since 2002. The telescope can be used as an aperture-synthesis array for imaging, as well as a phased array to study compact, time varying radio sources such as pulsars.

Around 2019, a major upgrade of the GMRT (uGMRT) was completed, targeted to improve its sensitivity by a factor of up to three, making it a more versatile instrument providing (a) near seamless frequency coverage from about 100 to 1500 MHz; (b) improved receiver systems with higher G/Tsys; (c) maximum instantaneous bandwidth of 400 MHz; (d) matching improvements in infrastructure and computing.

This upgrade will maintain the GMRT as one of the most sensitive facilities in the world in the 100 to 1500 MHz range, till the SKA phase 1, and will also drive a new wave of interesting new results. Prof Yashwant will present astatus update on the uGMRT, including an appraisal of how well the upgrade has worked, learnings from the upgrade, and a sample of the new science coming from it.

Several new features have been implemented following the upgrade. Amongst these is the capability for VLBI observations using the phased array voltage beam of the GMRT, where, given its unique geographical location, the GMRT can play a major role in global VLBI networks. Successful test observations have been carried out with telescopes in Europe, Australia, and China. On the software side, new pipelines have been developed to facilitate analysis of wideband interferometry data from the uGMRT (including polarimetric data), as well as for beamformer data. Quality polarimetric observations have now become possible with the uGMRT.

Looking into the future, a major new development is the ongoing installation and commissioning of a 2 Pflop, GPU-based back end for real-time detection of transients. On a longer time scale of a decade or so, a proposal for an expanded GMRT (eGMRT) is under discussion, which envisages increasing the number of antennas and/or equipping each antenna with a focal plane array. These plans will keep the GMRT in the forefront in the years to come.