'PSF' menu help page


  The 'PSF' menu contains the following sub-menus:

  'Load':
      Load a PSF array from a FITS file.

  'Extract from image':
      Extract the PSF from the stellar field image, by superposition
      of a set of user-selected stars (referred to as 'PSF stars').

  'Repeat extraction':
      An accurate PSF estimation requires a good knowledge of the
      background emission and of the secondary sources which
      contaminate the 'PSF stars'. Better estimates of these quantities
      are available after having analyzed the stellar field image with
      the algorithm for stars detection, astrometry and photometry.
      The 'Repeat extraction' sub-menu allows the user to repeat
      automatically the PSF extraction procedure after analyzing the
      field, using the same options and parameters which have been
      applied in the first run of the PSF extraction procedure.
 
  'Post process':
      Modify the support of the retrieved PSF and smooth the PSF halo.

  'Normalize':
      Normalize the PSF array to total flux = 1. This task may be useful
      to normalize an external PSF, loaded from a file. Notice that the
      PSF extracted within XStarFinder is always normalized automatically.

  'Save':
      Save to a FITS file the current estimate of the PSF.