THE COSMIC ANISOTROPY TELESCOPE

The Cosmic Anisotropy Telescope (CAT) is a 3-element radio interferome ter of novel design for observing temperature fluctuations in the Cosm ic Microwave Background Radiation. The three horn-reflector antennas e ach have a diameter of 70 cm and are mounted on rails to provide basel ines between 1 and 5 m. The instrument can observe in a 500 MHz bandwi dth centred anywhere between 13 and 17 GHz and can reach a temperature sensitivity of a few muK per month of good observing. We have taken e xtreme care to ensure that uncalibrated instrumental offsets are absen t at this level. CAT observations should provide both confirmation of primordial fluctuations on an angular scale of about 0.5 degree and st rong constraints on current theories of galaxy formation.