Correlated noise in the COBE DMR sky maps

The {it COBE} DMR sky maps contain low-level correlated noise. We obtain estimates of the amplitude and pattern of the correlated noise from three techniques: angular averages of the covariance matrix, Monte Carlo simulations of two-point correlation functions, and direct analysis of the DMR maps. The results from the three methods are mutually consistent. The noise covariance matrix of a DMR sky map is diagonal to an accuracy of better than 1%. For a given sky pixel, the dominant noise covariance occurs with the ring of pixels at an angular separation of $60 deg$ due to the $60 deg$ separation of the DMR horns. The mean covariance at $60 deg$ is $0.45% ^{+0.18}_{-0.14}$ of the mean variance. Additionally, the variance in a given pixel is $0.7%$ greater than would be expected from a single beam experiment with the same noise properties. Auto-correlation functions suffer from a $sim 1.5; sigma$ positive bias at $60 deg$ while cross-correlations have no bias. Published {it COBE} DMR results are not significantly affected by correlated noise. COBE pre-print 94-Comment: 11 pages + 3 figures, post-script fil