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The Second Measurement of Anisotropy in the Cosmic Microwave Background Radiation at 0\fdg5 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 previous measurement (\cite{mei93a}). The data in each channel clearly show structure correlated with IRAS 100 \micron\ dust emission. The spectrum of the structure in the 6, 9 and 14 cm$^{-1}$ channels is described by $I_ν\proptoν^βB_ν(T_{dust})$, where $β$ = 1.3 and $T_{dust}$ = 19~K and $B_ν$ 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 best fit foreground spectrum for the three lower channels, we find an upper limit to CMBR fluctuations of $ΔT/T = \langle \frac{C_l~l(l+1)}{2π}\rangle^{\frac{1}{2}} \leq 1.3\times 10^{-5}$ at the 95\% confidence level. The result is for a flat band power spectrum and does not include a 10\% uncertainty in calibration. It is consistent with our previous observation in the region.