Detection of Cosmic Microwave Background Anisotropy by the Third Flight of MSAM

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 07 .5 beam size in four bands from 5 to 20 cm 21 . 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 mm IRAS Sky Survey Atlas; from this comparison we determine an effective emissivity spectral index between 100 mm and 444 mm of . Analysis of our measurement of CMBR anisotropy shows 1.46 5 0.28 that for Gaussian-shaped correlation functions with vc 5 07 we place a limit on total rms anisotropy of (90% confidence interval, including calibration error). The band-power limits 25 25 2.2 # 10 ! DT/T ! 3.9 # 10 are at , and at (1 j limits, including 1/2 116 118 AdTS { Al(l 1 1)C /2pS 5 50 mK l 5 160 AdTS 5 65 mK l 5 270 l 211 213 calibration error). The corresponding limits with statistical errors only are and 113 AdTS 5 50 mK AdTS 5 29 , respectively. These measurements are consistent with a standard adiabatic cold dark matter model; we 114 65 mK 210 discuss constraints on h, n, and the redshift of reionization. Subject headings: balloons — cosmic microwave background — cosmology: observations — infrared: ISM: continuum