NONCOSMOLOGICAL SIGNAL CONTRIBUTIONS TO THE COBE1 DMR ANISOTROPY MAPS

We examine the COBE Differential Microwave Radiometer (DMR) data for e vidence of noncosmological source contributions. The DMR maps are cros s-correlated with maps of rich clusters, extragalactic IRAS sources, H EAO 1 A-2 X-ray emission, and 5 GHz radio sources. We limit the rms co ntributions from these sources on a 7-degrees angular scale to less th an 10 muK (95% confidence level) in the DMR maps, although the Large M agellanic Cloud probably contributes approximately 50 muK to a limited region of the sky. Thus, our previous interpretation that the fluctua tions in the COBE DMR data are most likely due to cosmic fluctuations at the surface of last scattering remains intact. The Comptonization p arameter for hot electrons traced by rich clusters is limited to delta y < 2 x 10(-6) (95% confidence level) averaged over the 7-degrees DMR beam.