XMM-Newton Science Analysis System


eboxdetect (eboxdetect-4.29) [xmmsas_20230412_1735-21.0.0]

Algorithm

subroutine eboxdetect

  Rebin images by linear factors of 1, 2, 4 ...
    (number of rebinning steps specified by parameter)

  Loop over rebinned images: 
    Loop over image pixels:
      IF within area marked by detection mask 
           (if mask flag is 'false': loop over all image pixels)
      THEN
        Loop over all instruments:
          Loop over all energy bands:

            IF local detect THEN 
              Perform simple box search:
                1) Accumulate counts in 3 x 3 or 5 x 5 pixel source box.
                2) Accumulate counts in background area (16 background pixels 
                   from 5 x 5 box or 24 background pixels from 7 x 7 box 
                   centered on source box)
                3) Calculate statistical probability of excess in source box.
                   Correct for border effects if source/background pixels
                   are at image/detection mask border).  
                4) Accumulate combined statistical probability of excesses 
                   in all energy bands of all instruments.
            END IF
        
            IF map detect THEN
              Perform matched filter/box search:
                1) Accumulate PSF weighted counts (PSF centred on 5 x 5 box) 
                   and/or non-weighted counts (to handle extended objects)
                   in 5 x 5 pixel box. 
                2) Calculate statistical probability of excess with respect
                   to background map. Correct for border effects if 
                   source/background pixels are at image/detection mask 
                   border.  
                3) Accumulate combined statistical probability of excesses 
                   in all energy bands of all instruments.
            END IF

          END Loop
        END Loop

        IF combined statistical probability of excess exceeds threshold THEN
           Write source records to EBOXDETECT source table.
           Add fluxes and hardness ratios.
        END IF

      END IF
    END Loop
  END Loop

end subroutine  eboxdetect