Detection of Cosmic Microwave Background Anisotropy by the Third Flight of the Medium-Scale Anisotropy Measurement

The third flight of the Medium-Scale Anisotropy Measurement (MSAM1), in 1995 June, observed a new strip of sky, doubling the sky coverage of the original MSAM1 data set. MSAM1 observes with a 05 beam size in four bands from 5 to 20 cm-1. From these four bands we derive measurements of cosmic microwave background radiation (CMBR) anisotropy and interstellar dust emission. Our measurement of dust emission correlates well with the 100 μm IRAS Sky Survey Atlas; from this comparison we determine an effective emissivity spectral index between 100 μm and 444 μm of 1.46±0.28. Analysis of our measurement of CMBR anisotropy shows that for Gaussian-shaped correlation functions with θc = 03, we place a limit on total rms anisotropy of 2.2×10−5<ΔT/T<3.9×10−5 (90% confidence interval, including calibration error). The band-power limits are δT ≡ l(l+1)Cl/2π½=50+16−11 μK at l=160, and δT=65+18−13 μK at l=270 (1 σ limits, including calibration error). The corresponding limits with statistical errors only are δT=50+ 13−9 μK and δT=65+ 14−10 μK, respectively. These measurements are consistent with a standard adiabatic cold dark matter model; we discuss constraints on h, n, and the redshift of reionization.