A 5-GHZ INTERFEROMETER FOR MICROWAVE BACKGROUND STUDIES

A description is given of a 5-GHz, two-element very short baseline int erferometer operated at Jodrell Bank for degree-scale studies of Galac tic, point source and intrinsic cosmic microwave background emission. This is a high-sensitivity interferometer with 20-K system noise and a bandwidth of nearly 350 MHz. Its phase stability from day to day is b etter than 2 degrees and allows independent data from separate days to be stacked. The interferometer gives receiver noise limited performan ce with an rms of 25 mu K in 2 min (0 degrees.05 in RA) from 26d of da ta. The performance of the interferometer is illustrated with observat ions at Dec. = 40 degrees for baselines of 11 lambda and 30 lambda. Th e astronomical potential of the interferometer is described.