Results of 40 simulations. (a) Variance in the images made before and after calibration. Three calibration scenarios are shown, where the calibration without a diffuse sky model gives lower noise, probably due to overfitting. (b) Correlation of the diffuse foreground with the residual. When the diffuse sky model is included in the calibration, much of the diffuse sky model is preserved. However, in other calibration scenarios, the diffuse sky is significantly suppressed (this is the reason for excluding short baselines in these calibration scenarios).