Figure 7.3: Sky area as a function of net exposure time for catalogue fields. The upper histograms show the 'nominal' sky area without corrections for field overlaps or the off-axis reduction in effective area. The lower histograms show the 'actual' sky area taking both these effects (and the smaller effects of CCD gaps and bad columns) into account.
Red: EPIC PN observations; green: EPIC MOS-1 observations; cyan: EPIC MOS-2 observations. Note that the MOS histograms overlap.