WIENER FILTERING OF THE COBE DIFFERENTIAL MICROWAVE RADIOMETER DATA

We derive an optimal linear filter to suppress the noise from the COBE Differential Microwave Radiometer (DMR) sky maps for a given power sp ectrum. We then apply the filter to the first-year DMR data, after rem oving pixels within 20-degrees of the Galactic plane from the data. We are able to identify particular hot and cold spots in the filtered ma ps at a level 2 to 3 times the noise level. We use the formalism of co nstrained realizations of Gaussian random fields to assess the uncerta inty in the filtered sky maps. In addition to improving the signal-to- noise ratio of the map as a whole, these techniques allow us to recove r some information about the cosmic microwave background anisotropy in the missing Galactic plane region. From these maps we are able to det ermine which hot and cold spots in the data are statistically signific ant, and which may have been produced by noise. In addition, the filte red maps can be used for comparison with other experiments on similar angular scales.