Maps of the residual energy correction factor in stacked observations, after applying our correction to this in the individual observations. The units are per cent per keV. The panels show revolution bins of 0–500, 500–1000, 1000–1500, 1500–2000, 2000–2500 and 2500–3000 (left to right and top to bottom). The uncertainty of these values is not the same across the detector or in time, so we use 8 and 16 pixel binning. The statistical uncertainty is much larger in the bottom-left area because of the non-uniformity of the calibration source. Pixels where the uncertainty is larger than 10⁻³ keV⁻¹ are not shown.