An Instrument for Investigation of the Cosmic Microwave Background Radiation at Intermediate Angular Scales

摘要

We describe an off-axis microwave telescope for observations of the anisotropy in the cosmic micro- ave background (CMB) radiation on angular scales between 0.5 and 3 deg. The receiver utilizes cryogenic high electron mobility transistor (HEMT) amplifiers and detects the total power in multiple 3 GHz wide channels. Both frequency and polarization information are recorded allowing discrimination between CMB radiation and potential foreground sources and allowing checks for systematic effects. The instru- ental radiometric offset is small (～ mK). Data are taken by rapidly sampling while sweeping the beam many beamwidths across the sky. After detection, a spatio-temporal filter is formed in software that optimizes the sensitivity in a multipole band in the presence of atmospheric fluctuations.