Proposed Very Long Baseline Interferometry at 103 MHz in India

Abstract

Three radio telescopes operating at 103 MHz are being installed at Ahmedabad, Rajkot and Surat separated by about 200 km from each other for observing interplanetary scintillations (IPS) of compact radio sources for study of solar wind plasma dynamics as well as radio source size measurements for cosmological studies. Of these, two radio telescopes at Ahmedabad and Rajkot have been commissioned and started synchronous daily observations of IPS of a few compact radio sources with relative time accuracy of about ± 1 millisec. The third telescope at Surat is expected to go in operation by the end of 1983. As soon as all the three telescopes go in for simultaneous operation, it is proposed to (1) augment the telescope sensitivity so as to detect sources with flux density ~ 1 Jansky (2) incorporate better time and frequency standards at each station which can be synchronised to better than μs relative time accuracy (3) develop suitable receivers and data acquisition system for generating interference fringes using a general purpose computer and (4) take advantage of the availability of three telescopes to incorporate ‘closure phase and amplitude’ techniques which eliminate undesirable atmospheric and ionospheric phase distortions.