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Session 12 - Cosmology, Large-Scale Structure and Distance Scales.
Display session, Monday, June 10
Great Hall,

[12.01] The Contribution of Galactic Free-Free Emission to Anisotropies in the Cosmic Microwave Background Radiation Measured by MSAM

J. H. Simonetti, G. A. Topasna, B. Dennison (Virginia Tech)

The Medium Scale Anisotropy Measurement (MSAM) experiment has detected anisotropies in the cosmic microwave background radiation with an rms between about 30 \muK and 90 \muK. MSAM uses double-difference and single-difference demodulation signals from a chopped, 30^\prime beam at a number of frequencies between 170 and 680 GHz. We observed the region covered by MSAM using the Virginia Tech Spectral Line Imaging Camera (SLIC), a wide-field camera sensitive to faint interstellar H\alpha emission. We duplicated the MSAM chopping and demodulation procedure using samples from our H\alpha image (after the subtraction of a continuum image and smoothing to a 30^\prime beam). The rms in our double-difference and single-difference demodulation signals are 4.4 and 3.0 Rayleighs, respectively. The implied rms for the microwave brightness temperature of the interstellar plasma is <1 \muK at 170 GHz. Thus the MSAM anisotropies are not significantly contaminated by foreground Galactic emission irregularities. This research was supported by NSF grant AST-9319670 and a grant from the Horton Foundation to Virginia Tech.

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