MSAM1-94 - REPEATED MEASUREMENT OF MEDIUM-SCALE ANISOTROPY IN THE COSMIC MICROWAVE BACKGROUND-RADIATION

The second flight of the Medium-Scale Anisotropy Measurement (MSAM1-94 ) observed the same field as the first flight (MSAM1-92) to confirm ou r earlier measurement of cosmic microwave background radiation (CMBR) anisotropy. This instrument chops a 30' beam in a three-position patte rn with a throw of +/-40' and simultaneously measures single- and doub le-differenced sky signals. We observe in four spectral channels cente red at 5.6, 9.0, 16.5, and 22.5 cm(-1),providing sensitivity to the pe ak of the CMBR and to thermal emission from interstellar dust. The dus t component correlates well with the IRAS 100 mu m map. The CMBR obser vations in our double-difference channel correlate well with the earli er observations, but the single-difference channel shows some discrepa ncies. We obtain a detection of fluctuations in the MSAM1-94 data set that match CMBR in our spectral bands of Delta T/T = 1.9(-0.7)(+1.3) x 10(-5) (90% confidence interval, including calibration uncertainty) f or total rms Gaussian fluctuations with correlation angle 0.degrees 3, using the double-difference demodulation.