XMM-Newton Science Analysis System


omqualitymap (omqualitymap-1.6) [22.0.0-9173c7d25-20250127]

Setting of bit 4 (Modula-8 pattern)

The algorithm uses a simple algorithm to search for a line of pixels in the horizontal$\backslash$vertical directions to the left$\backslash$right and top$\backslash$bottom of the centre of given source. If 7 or more unbinned pixels are brighter than the corresponding ones along an adjacent column or row a modular-8 pattern may exist around the source. If at least 2 such patterns are found it is concluded that a definite modular-8 pattern exists. All pixels within a box of minimum width and height 21 pixels, centred on the source, have bit 4 set. The algorithm will attempt to determine the maximum distance of the pattern from the centre of the star and adjust the width and height accordingly.