Comparison between the covariance predicted by theory and measured from simulations, for the three masks. Top row: variance divided by the power spectrum squared, and lower three rows: correlation. In all panels the simulated line is a rolling average over 50 ℓs, and the shaded region is the standard deviation over this range. The covariance shown here is for the shear E-mode power spectrum in the lowest redshift bin, without shape noise.