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Radio Astronomy Centre

National Centre for Radio Astrophysics

Tata Institute of Fundamental Research

      Over the 43 years, the ORT has produced many important astronomical results on radio galaxies, quasars, supernovae, pulsars, the interstellar and interplanetary media, etc. One of the most successful observational programs carried out for many years at Ooty was to determine the angular structures of hundreds of distant radio galaxies and quasars by the technique of lunar occultation. The application of this unique database to observational cosmology provided independent evidence against the Steady-State theory of Universe and supported the Big-Bang model of the Universe.The telescope is currently being used mainly for the study of pulsars, radio recombination lines and interplanetary scintillations.

Interplanetary Scintillation

      The new technique developed at Ooty to study the interplanetary scintillation observations provides valuable information about the solar wind and solar-wind magnetic storms that affect the near-Earth environment. Major eruptive events on the Sun, such as flares or coronal mass ejections (CMEs), can have a profound influence on the terrestrial environment. CMEs can interact with Earth's magnetosphere to generate major geomagnetic storms and substorms, sometimes affecting communication and power grid systems and accelerating energetic particles that have been known to damage communications satellites and may harm astronauts working in space. Ooty scintillation measurements are useful in identifying and understanding the evolution of disturbances caused by powerful CME events in the Sun-Earth distance and forecasting the arrival of such large events at the near-Earth space.

      The objective of the Ooty scintillation study is to significantly advance the understanding of the three-dimensional (3-D) structure and evolution of CMEs and their interaction with the interplanetary medium and terrestrial magnetosphere using combined imaging, radio, and in-situ measurements from spacecraft. Ooty measurements have been successfully employed to track CMEs from Sun to Earth distance and they have elucidated the evolution of the 3-D structure and speed of CMEs in the inner heliosphere. Interplanetary scintillation observations also provide a valuable database to understand the Space Weather changes and its predictability.

Very Long Baseline Interferometry (VLBI)

      For example, by using atomic clocks, which provide excellent time and frequency standards, ORT has been used to do very long baseline interferometry (VLBI) by combining the radio waves received by them with those received by radio telescopes in West Germany, Holland, England, Japan, Poland, China, and Russia. This has enabled celestial objects like radio galaxies and quasars to be observed with very high resolution, equivalent to that obtained by a telescope with an aperture size of about 5000 km.