Galactic foreground contribution to the BEAST cosmic microwave background anisotropy maps

We report limits on the Galactic foreground emission contribution to the Background Emission Anisotropy Scanning Telescope (BEAST) Ka- and Q-band CMB anisotropy maps. We estimate the contribution from the cross-correlations between these maps and the foreground emission templates of an H alpha map, a destriped version of the Haslam et al. 408 MHz map, and a combined 100 mu m IRAS DIRBE map. Our analysis samples the BEAST similar to 10 degrees declination band into 24 one-hour (R. A.) wide sectors with similar to 7900 pixels each, where we calculate (1) the linear correlation coefficient between the anisotropy maps and the templates; (2) the coupling constants between the specific intensity units of the templates and the antenna temperature at the BEAST frequencies; and (3) the individual foreground contributions to the BEAST anisotropy maps. The peak sector contributions of the contaminants in the Ka-band are of 56.5% free-free with a coupling constant of 8.3 +/- 0.4 mu K R-1, and 67.4% dust with 45.0 +/- 2.0 mu K MJy(-1) sr(-1). In the Q band the corresponding values are of 64.4% free-free with 4.1 +/- 0.2 mu K R-1 and 67.5% dust with 24.0 +/- 1.0 mu K MJy(-1) sr(-1). Using a lower limit of 10% in the relative uncertainty of the coupling constants, we can constrain the sector contributions of each contaminant in both maps to <20% in 21 (free-free), 19 (dust), and 22 (synchrotron) sectors. At this level, all these sectors are found outside of the vertical bar b vertical bar = 14.degrees 6 region. By performing the same correlation analysis as a function of Galactic scale height, we conclude that the region within b = +/- 17.degrees 5 should be removed from the BEAST maps for CMB studies in order to keep individual Galactic contributions below similar to 1% of the map's rms.