XMM-Newton Science Analysis System


eregionanalyse (especget-1.19) [xmmsas_20050815_1803-6.5.0]

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Optimisation

   SNRMAX=0

   TOTAL_SRC_COUNTS = counts in the input image within the source region
                      corrected for the encircled energy fraction of the
                      source region

   Loop TEST_RADIUS = 1 to 300 arcseconds

      EEF = calculate encircled energy fraction for this TEST_RADIUS
             using the PSF relevant for this Epic camera at the
             position of the source box for a photon energy of 1.5 keV 

      SRC_COUNTS = TOTAL_SRC_COUNTS * EEF

      BGD_COUNTS = background counts per arcsec^2 * PI * TEST_RADIUS**2

      S/N ratio = SRC_COUNTS / sqrt(SRC_COUNTS + BGD_COUNTS)

      if (S/N ratio > SNRMAX) {
         SNRMAX = S/N ratio
      }

   EndLoop