Cross-identification was achieved using the input sources above 10 counts and 30 counts for 10 ks and 100 ks exposures respectively. Lowering the count limits yields more cross-identifications but increases considerably the number of spurious detections. In the following we discuss some important points.
Differential number counts as a function of flux.
The solid line is exact match between detected and input counts while the dashed lines are for two-fold differences.