XMM-Newton Science Analysis System


omichain (omichain-1.74.3) [xmmsas_20190531_1155-18.0.0]

Processing of the mosaiced sky-images

This functionality was introduced into SAS 9 to allow source-detection on the mosaiced sky-images. It will only occur if the optional parameter processmosaicedimages is set to true (default is false).

The way in which the mosaiced sky-images are processed is shown in Figure 4 and it works in the following way:

1. Loop through each OM filter present and:
   • Run omdetect on the mosaiced sky-image file to produce an output FITS source-list file. The SRCLIST FITS table in this file will contain RA and Dec coordinates, computed using the WCS keywords in the FITS header. The photometry will have been done using the mosaiced EXPOSURE image in the sky-image file, and no corrections will have been done for coincidence-losses.

   • Run ommag on the source-list file to add instrumental magnitudes to it.

   • Run omqualitymap to set source-quality flags using the QUALITY image in the mosaiced sky-image file.

2. Run omsrclistcomb, using these new source-list files (one per filter) as the input files, to produce a second observation source-list file.

3. Run ommergelists to create a third observation source-list file from the merging of the first two.