XMM-Newton Science Analysis System


omregion (omregion-2.15) [xmmsas_20230412_1735-21.0.0]

Algorithm

   subroutine omregion

   read in source list

   if (srcnumber > number of sources in list) issue fatal error

   locate the srcNumber'th source 
    
   x = XPOS
   y = YPOS
   fwhm = FHWM ! obtained from source list rather than the CAL

   r1 = fwhm * srcRadius

   nearest = 1.e30
   loop over all sources except the selected source
      if (distance to this source < nearest) then
         nearest = distance to this source
         size = fwhm of this source
      endif
   endloop


   if (r1 > (nearest - nfwhm * size)) then
      
        r1 = nearest - nfwhm * size
  
        warn that the size of the extraction region is begin reduced

        if (r1 < 0) then

          warn that the source is unavoidably contaminated

          r1 = fwhm
 
        endif


   rInner = r1 * bkgInner
   rOuter = r1 * bkgOuter


   ncontaminating = 0

   loop over all other sources
     compute distance to source dist
     if (rInner < (dist - nfwhm * fwhm of this source) < rOuter)  then
     store contaminating source x, y, fwhm
     ncontaminating++
   end loop

   open source region file

   write out source region file
   
   close source region file

   open background region file

   write out background annulus

   loop over ncontaminating sources
      write out exclusion circle for this source
   end loop

   close background region file

   end subroutine omregion