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SMOOTHMAP

SMOOTHMAP
  WARNING:
  This function has been deprecated, and replaced by SKYMAP_SMOOTH. I
  recommend using that function instead of this one.

Name


  SMOOTHMAP

Purpose


  This procuedure creates a smoothed map of some quantity sampled,
  with uncertainty, at irregualr points across the sky. It uses a
  gaussian smoothing filter to average nearby data points and improve
  noise statistics. The algorithm is taken from Lombardi and Alves
  2001. This implementation was written to generate Av maps from the
  output of the NICER algorithm (also described in Lombardi and Alves
  2001, and implemented in the procedure NICER.pro)

Calling Sequence


  SMOOTHMAP, val, err, x, y, map, errmap, ctmap, head,
            [cdelt = cdelt, fwhm = fwhm, out = out, /CLIP,
            /GALACTIC, /CARTESIAN, /VERBOSE, /ITERATE]

Inputs


  val: The sampled values to smooth over
  err: The uncertainties on the sampled errors (sqrt(variance))
    x: The x position of the sampled values (treated as a spherical
      coordinate in DEGREES)
    y: The y position of the sampled values (treated as a spherical
      coordiante in DEGREES)
;

Keyword Parameters


    cdelt: A scalar defining the pixel size of the map in
            DEGREES. If not defined, cdelt will be set to fwhm / 2.
      fwhm: The FWHM of the smoothing kernel, in DEGREES. If not
            supplied, the fwhm will be set so that, on average, a 1 fwhm
            diameter circle surrounds 50 datapoints.
      out: Write a FITS file of the results. The output files will be
            named out_map.fits, out_err.fits, and out_ct.fits.
      CLIP: If set, the procedure will iterate and reject outlier data
            points.
  GALACTIC: If set, the coordinates are assumed to be in galactic
            coordinates. This does not affect the map calculation, but does
            impact the header file. If not set, the FK5 system is
            assumed.
  CARTESIAN: If set, the input and output are in a cartesian
            (non-spherical) coordinate system
  VERBOSE: If set, information about the procedure is printed to the terminal.
  ITERATE: Used internally for the sigma clipping process. Do not set
            this manually.

Optional Outputs


    map: A variable to hold the smoothed map
  errmap: A variable to hold the error (sqrt(variance)) on the smoothed map
  ctmap: A variable to hold the map giving the number of sources
          which went into the calculation of each pixel
    head: A variable to hold the header of the map (A string array)

Restrictions


  For pathological cases (sampled points straddle the poles or l=360
  deg line), the map dimensions will be calculated incorrectly.
 

Category


  image processing
 

Modification History


  November 2008: Written by Chris Beaumont based on code by Jon
                Swift. Written to independently reproduce and
                speed up that code.
  December 1 2008: Fixed several bugs in error calculation. cnb.
  December 4 2008: Fixed things so NANs in the input val variable
                  are ignored. cnb.
  April 15 2009: Added CARTESIAN keyword
  March 2010: Deprecated and replaced by skymap_smooth. cnb.



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