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Radio Astronomy Centre

National Centre for Radio Astrophysics

Tata Institute of Fundamental Research

      The Ooty Radio Telescope (ORT, as it is known) is a cylindrical paraboloid of reflecting surface, 530 m long and 30 m wide, placed on a hill whose slope of about 11 degree in the north-south direction which is the same as the latitude of the location of ORT. This makes it possible to track celestial objects for about 10 hours continously from their rising in east to their setting in the west by simply rotating the antenna mechanically along its long axis. The antenna beam can be steered in the north-south direction by electronic phasing of the 1056 dipoles placed along the focal line of the reflector. The reflecting surface is made up of 1100 thin stainless steel wires, each 530 m long. It is supported by 24 parabolic frames separated by 23 m from each other.

      The telescope is operated at 326.5 MHz (a wavelength of 0.92 m) with 15 MHz usable bandwidth. The large size of the telescope makes it highly sensitive. As an example, it is in principle capable of detecting signals from a mere 1 watt radio station located ten million kilo meter away in space.

       The Ooty Radio Telescope has been designed and fabricated fully indigenously. The ORT completed in 1970 and continues to be one of the most sensitive radio telescopes in the world. Observations made using this telescope have led to important discoveries and to explain various phenomena occurring in our Solar system and in other celestial bodies.

Up-gradation of ORT :

       An array of 1056 half-wave dipoles in front of a 90 degrees corner reflector forms the primary feed of the telescope. The front-end receiver system of the ORT was upgraded with a low noise amplifier (Tex = 50 K) and a strip line diode-switch controlled phase shifter following each of the 1056 dipoles. This up-gradation improved the sensitivity of the ORT substantially. Additionally the declination-setting and monitoring system was computerized leading to enhanced stability. A new local oscillator phase shifter with increased accuracy has improved the response of ORT over the entire 15 MHz bandwidth and also increased the declination range visible to the ORT. The present system supports electronic steering to declinations between -60 and +60 degrees. The telescope can be operated in either total power or correlation mode. In each mode, 12 beams are formed and Beam 1 is the southern most beam and Beam 12 is the northern most. These 12-beam systems are useful in sky-survey type of observations. Recently, the reflecting surface of the ORT has been refurbished. A new digital back-end has been built for the ORT by the colleagues at Raman Research Institute (RRI), Bangalore.

Backends:

Analog Correlator: Used for IPS observations.
New Digital backend System

Ongoing Projects:

IPS observations
Pulsar observations
Spectral line observations

Request for ORT Time: Please write a brief scientific proposal outlining your experiment and the required telescope time. You may have to travel to Ooty to conduct your observations - remote observing is not an option available. Send your observing proposal to Centre Director, NCRA and a copy to Head, RAC.

More information on the ORT system can be found in:

1. Swarup, G., et al, 1971, Nature Physical Sciences, 230, 185.
2. Subrahmanyan, R., 1989, Ph.D. Thesis, Indian Institute of Science, Bangalore.
3. Manoharan, P.K., 1991, Ph.D. Thesis, TIFR, University of Bombay.
4. Selvanayagam, A.J., Praveenkumar, A., Nandagopal, D., Velusamy, T., 1993, 1ETE Technical Review, 10, No. 4, 333.
5. Roshi, A.D., 1995, M.Sc. Thesis, Poona University.
6. Ramesh Bhat, N.D., 1998, Ph.D. Thesis, Poona University.