THE 2ND MEASUREMENT OF ANISOTROPY IN THE COSMIC MICROWAVE BACKGROUND-RADIATION AT 0.DEGREES-5 SCALES NEAR THE STAR MU PEGASI

During the fifth flight of the Microwave Anisotropy Experiment (MAX5), we revisited a region with significant dust emission near the star mu Pegasi. A 3.5 cm(-1) low-frequency channel has been added since the p revious measurement (Meinhold et al. 1993a). The data in each channel clearly show structure correlated with IRAS 100 mu m dust emission. Th e spectrum of the structure in the 6, 9, and 14 cm(-1) channels is des cribed by I-v proportional to nu(beta)B(nu) (T-dust), where beta = 1.3 and T-dust = 19 K and B-v is the Planck function. However, this model predicts a smaller amplitude in the 3.5 cm(-1) band than is observed. Considering only linear combinations of the data independent of the b est-fit foreground spectrum for the three lower channels, we find an u pper limit to CMBR fluctuations of Delta T/T = (C(l)l(l + 1)/2 pi)(1/2 ) less than or equal to 1.3 x 10(-5) at the 95% confidence level. The result is for a flat-band power spectrum and does not include a 10% un certainty in calibration. It is consistent with our previous observati on in the region.