XMM-Newton Science Analysis System


omcosflag (omcosflag-1.35) [22.0.0-9173c7d25-20250127]

Description

The shift and add process means that the counts observed in each pixel of an OSW image may have been accumulated in several different detector pixels. This task takes the OM tracking history and applies it to the map of bad pixels defined in the CCF. The result is an increase in the area of the OSW image contaminated by bad pixels.

The task produces a bad-pixel 2-d map which is stored in the QUALITY extension of the FITS input$\backslash$output image file. From SAS 9.0 onwards, this map is a 16-bit image, compared to the earlier 8-bit image. This change has occurred because SAS 9.0 introduced the functionality of source-detection on mosaiced sky-images. In order to allow the quality-flagging of sources detected on such images, the QUALITY image allows flagging information obtained from source-detection on exposure images to be stored and then retrieved to set source QUALITY flags. This process is explained in the SAS document omqualitymap- a new OM program.

The QUALITY image will be used by other OM programs, including omdetect, ommodmap and ommosaic. The binning of the bad pixel map, and the offset of the science window, are read from the headers of the OSW image, which is an input of the task.