Screening Results for the 1XMM Catalogue

The images below consist of all observations used for the 1XMM catalogue. The number of sources per image pixel are added up and displayed as intensity. In the left hand panels all sources are shown. In the middle panel all 'good' sources are shown, that is, all sources where Flag #1 ('False detection') is not set (=F). The right hand panels show all sources that were flagged as false (Flag #1 is set to T).


1XMM PN screening results

Both the left and right hand images show the problems with false detections in the PN: Apart from out of time events, the repeated detection of the central source in the adjacent (lower) CCD and the halo of false detections around the central bright source, there are also a few hot pixels (in the right upper quadrant, and at the bottom to the left of the center) and a short bright segment (second upper CCD from the left close to the center line). It becomes clear from the central image that some of the hot pixels have been missed. On the other hand, the central image shows clearly the random distribution of all sources (except for the central source which appears in about the same location in most observations).


1XMM M1 screening results

The persistent false detections in the M1 image are mainly a bright segment at the top of the central CCD and the corners of the central CCD and CCD #4 (see also the examples here). Furthermore, the RGA diffraction spike (the horizontal central line) and, fainter, the out of time events perpendicular to it in the central CCD are obvious, as well as the halo of spurious detections around the central source.


1XMM M2 screening results

The M2 images show a few brighter spots that have not been screened, most of this would be due to warm pixels which were not meant to be screened. A short segment is obvious at the upper left corner of the central CCD, though this could be also due to a chance alignment of a couple of warm pixels (nothing had been obvious here during the screening process). The RGA diffraction spike (only one-sided), out of time events (in the same direction as the RGA diffraction) and the halo due to spurious detections in the halo of the central source are also obvious features.

Screening Notes Example: Version 29.05.2003