An aperture-synthesis interferometer at Ooty for operation at 327 MHz

A 3.5-km long interferometer consisting of the 530 by 30 m Ooty radio telescope, two 13.5-m diameter dishes, and a 5-m diameter dish are described. For generating coherent local-oscillator signals for the interferometer, a simple phase-stable radio link has been developed which uses the sum-frequency method proposed for the VLA antenna. The interferometer, expected to be in operation in 1973, will provide a resolution of about 0'.8×5'.5 arc at 327 MHz and will be able to detect a radio source of flux density 2 × 10^-28. Wċm^-2Hz^-1with a S/N ratio of 5 to 1. A proposed 10-km long synthesis interferometer consisting of the Ooty telescope and 36 dishes of 5-m diameter is also described. At 327 MHz, this instrument will provide beamwidths of 15" by 3" arc and 15" by 20" arc at declinations of 0° and 30°, respectively. It will have a sensitivity of about 10^-28Wċm^-2Hz^-1for a 9.5-h observing period.