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 our earlier measurement of cosmic microwave background radiation (CMBR) anisotropy. This instrument chops a 30\\\ beam in a 3 position pattern with a throw of \±40\, and simultaneously measures single and double differenced sky signals. We observe in four spectral channels centered at 5.6, 9.0, 16.5, and 22.5~\, providing sensitivity to the peak of the CMBR and to thermal emission from interstellar dust. The dust component correlates well with the \\\ 100~\\\ map. The CMBR observations in our double difference channel correlate well with the earlier observations, but the single difference channel shows some discrepancies. We obtain a detection of fluctuations in the MSAM1-94 dataset that match CMBR in our spectral bands of \Δ T/T = 1.9+1.3-0.7\× 10⁻⁵ (90\% confidence interval, including calibration uncertainty) for total rms Gaussian fluctuations with correlation angle 0\3, using the double difference demodulation.