OBSERVATIONS OF ATMOSPHERIC NOISE FLUCTUATIONS WITH A METER BASE-LINEINTERFEROMETER IN THE 13-17 GHZ BAND

This paper describes the atmospheric noise fluctuations that we have o bserved with the Cosmic Anisotropy Telescope (CAT) at Cambridge. The C AT is a short baseline radio interferometer designed to make observati ons of primordial anisotropies in the Cosmic Microwave Background Radi ation at angular scales between 20 arcminutes and 1 degree. During cle ar weather the observations are limited by receiver noise, whereas emi ssion and scattering from clouds limits the sensitivity of the instrum ent during rain and cloudy weather on the very shortest baselines. Flu ctuations in the correlated antenna temperature up to 100 mK have been seen, with a typical coherence time of 10 seconds.