DETECTION OF COSMIC MICROWAVE BACKGROUND ANISOTROPY BY THE 3RD FLIGHTOF THE MEDIUM-SCALE ANISOTROPY MEASUREMENT

The third flight of the Medium-Scale Anisotropy Measurement (MSAM1), i n 1995 June, observed a new strip of sky, doubling the sky coverage of the original MSAM1 data set, MSAM1 observes with a 0.degrees 5 beam s ize in four bands from 5 to 20 cm(-1). From these four bands we derive measurements of cosmic microwave background radiation (CMBR) anisotro py and interstellar dust emission. Our measurement of dust emission co rrelates well with the 100 mu m IRAS Sky Survey Atlas; from this compa rison we determine an effective emissivity spectral index between 100 mu m and 444 mu m of 1.46 +/- 0.28. Analysis of our measurement of CMB R anisotropy shows that for Gaussian-shaped correlation functions with theta(c) = 0.degrees 3, we place a limit on total rms anisotropy of 2 .2 x 10(-5) < Delta T/T < 3.9 x 10(-5) (90% confidence interval, inclu ding calibration error). The band-power limits are [delta T] = [l(l 1)C-1/2 pi](1/2) = 50(-11)(+15) mu K at l = 160, and [delta T] = 65(-1 3)(+18) mu K at l = 270 (1 sigma calibration error). The corresponding limits with statistical errors only are [delta T] = 50(-9)(+13) mu K and [delta T] = 65(-10)(+14) mu K, respectively. These measurements ar e consistent with a standard adiabatic cold dark matter model; we stat istical discuss constraints on h, n, and the redshift of reionization.