CSC uses combined (i.e. overlapping) Chandra observations for detecting X-ray sources. This allows the catalog to include significantly fainter sources than CSC 1.1. The set of overlapping observation
CAL The effect of changing count rates on the spectral response ismeasured by observing QAGN with similar spectral slope but with a range offluxes. For each of three EPIC exposures an overhead of 2.7k
