New cosmic microwave background power spectrum constraints from MSAM1

We present new cosmic microwave background (CMB) anisotropy results from th e combined analysis of the three flights of the first Medium Scale Anisotro py Measurement (MSAM1). This balloon-borne bolometric instrument measured a bout 10 deg(2) of sky at half-degree resolution in four frequency bands fro m 5.2 to 20 cm(-1) with a high signal-to-noise ratio. Here we present an ov erview of our analysis methods, compare the results from the three flights, derive new constraints on the CMB power spectrum from the combined data, a nd reduce the data to total power Wiener-filtered maps of the CMB. A key fe ature of this new analysis is a determination of the amplitude of CMB fluct uations at l similar to 400. The analysis technique is described in a compa nion paper (L. Knox).