This large Radio Telescope,  which  is in the form of a parabolic cylinder 530 M long X 30 M wide, operating at 327 MHz, is one of the largest telescopes in  the world  operating   at   Meter   wavelengths. It is four times  more  sensitive  than  the 76 meter diameter Jodrell Bank parabolic dish. The reflecting surface of the  telescope  consists  of 1100  thin  stainless steel  wires   which   are  supported   on  24 steel frames mounted on 24 equidistant steel towers.

The beam of the Telescope can be steered in the East-West direction by mechanical steering; whereas that in the North-South direction is done electronically. Radio signals are received by 1056 half wave dipoles at the focal line. Making use of an appropriate hill slope, the axis of the instrument has been kept parallel to the earth's axis of rotation.

The concept, design, fabrication and the resources for this telescope are fully indigenous. The telescope is operated by the Tata Institute of Fundamental Research under the auspices of the Department of Atomic Energy of the Government of India.

Scientific Programmes and Significant Results:

Lunar Occultation of Radio sources : The telescope is occupied for about 10 hours a day for survey and studies of radio sources in the sky by the Lunar occultation technique. Since February 1970, about 1200 radio sources have been observed.  The information, particularly of the angular size of weaker sources, has provided an independent evidence in support of the Big Bang model. The observations have also helped in understanding the physics  of radio  sources.

Interplanetary Scintillation Observations : The telescope is used for the study of compact  radio  sources  by observing the fluctuation of the intensity of radio signals from radio sources caused by the inter-planetary medium. This information is valuable for cosmological investigations and also gives one of the best early warnings  for  geomagnetic  disturbances.

Pulsars :  In a systematic search for pulsars, five pulsars have been discovered  at  Ooty. One of these is a pulsar with a large duty cycle of 21% as against a normal duty cycle of 3 to 5%. Certain characteristics of twelve weak pulsars also h.ve been determined.

The telescope is also used for other programmes such as flare stars, radio recombination line and deuterium  studies etc.

Future Developments : To enable studies of radio sources beyond the path of the moon  in the sky at high resolution  and with  high  sensitivity, a  synthesis  radio  telescope  consisting  of seven smaller antennae and the Ooty radio telescope over a baseline of 4 Km is being constructed. The aim is to achieve a resolution  of 40 sees of arc at 327 MHz, and a sensitivity of 5 million sky for 10 hours  integration  time   There are plans to extend the baseline Lo 9 Km which will improve the performance further  by  a factor  of about 2 to 3.

Technological fall-outs from the Ooty Radio Telescope Project : The indigenous design, fabrication and erection of the Ooty radio telescope has resulted in infusing confidence for self reliance in the whole area relating to the design and fabrication of large microwave antennae in  India.

A  novel  form  of  low  cost  but  high efficiency solar energy concentrator, based on a concept of the Ooty Radio Telescope, has been designed and its feasibility study is in progress.

Indian  Posts  &  Telegraphs  Department is happy to issue a stamp to commemorate achievements in Science   and Technology.

Source : Information Folder issued by Indian Posts & Telegraph Department, Government of India