NAME

       mFitplane - Use least squares to fit a plane to an image

SYNOPSIS

       mFitplane [-b border] [-d level] [-s statusfile] in.fits

DESCRIPTION

       Uses  least  squares  to fit a plane (excluding outlier pixels) to an image. It is used on
       the difference images generated using mDiff or mDiffExec.

OPTIONS

       -b border
              Number of border pixels to ignore at edges of image.

       -d level
              Turns on debugging to the specified level (1-3).

       -l     Level only: don't fit a slope; just get a zero level.

       -s statusfile
              Output and errors are written to statusfile instead of stdout.

ARGUMENTS

       in.fits
              Input FITS file is a difference file between  two  other  FITS  files,  as  can  be
              generated using mDiff.

RESULT

       The plane fit to the image is of the form:

        fit = A*x + B*y + C

       where  x  is  the  "horizontal"  pixel  offset from CRPIX1 in the FITS header and y is the
       "vertical" offset from CRPIX2.  Since all reprojected images use the same reference pixel,
       this is a uniform definition for x,y for the whole image set.

       The  fitting is a simple least squares, with an iterative loop to exclude points more than
       2 sigma (sigma defined as the rms from the previous loop).

       The rms output is the value computed above.  The xmin, ... ymax output correspond  to  the
       range  of  x,y  values found while fitting.  The rms is for information only but the xmin,
       ... ymax are used in the  background  fitting  (mBgModel).   crpix1  and  crpix2  are  the
       reference pixels for each axis, as determined from the FITS header.

MESSAGES

       OK     [struct   stat="OK",   a=A,  b=B,  c=C,  crpix1=crpix1,  crpix2=crpix2,  xmin=xmin,
              xmax=xmax, ymin=ymin, ymax=ymax, xcenter=xcenter,  ycenter=ycenter,  npixel=npixel,
              rms=rms,     boxx=boxx,    boxy=boxy,    boxwidth=boxwidth,    boxheight=boxheight,
              boxang=boxang]

       ERROR  Argument to -b (string) cannot be interpreted as an integer

       ERROR  Cannot open status file: statusfile

       ERROR  Image file filename missing or invalid FITS

       ERROR  FITS library error

       ERROR  general error

       WARNING
              Too few pixels to fit

       WARNING
              Too few pixels for bounding box

       WARNING
              Singular Matrix-1

       WARNING
              Singular Matrix-2

       WARNING
              allocation failure in ivector()

EXAMPLES

       $ mFitplane 2mass-atlas-990322n-j0640266.fits
              [struct  stat="OK",  a=-8.9198e-11,  b=-2.54173e-10,   c=5.24277e-05,   crpix1=808,
              crpix2=212.5,   xmin=-808,  xmax=167,  ymin=-210.5,  ymax=638.5,  xcenter=-320.871,
              ycenter=213.014,   npixel=314299,   rms=0.393003,    boxx=-320.92,    boxy=212.424,
              boxwidth=835.421, boxheight=509.274, boxang=-29.5537]

BUGS

       The drizzle algorithm has been implemented but has not been tested in this release.

       If  a  header  template  contains  carriage  returns  (i.e., created/modified on a Windows
       machine), the cfitsio library will be unable to read it properly, resulting in the  error:
       [struct stat="ERROR", status=207, msg="illegal character in keyword"]

       It  is  best  for the background correction algorithms if the area described in the header
       template completely encloses all of the input images in their entirety. If parts of  input
       images  are  "chopped  off"  by  the  header  template,  the background correction will be
       affected. We recommend you use an expanded header  for  the  reprojection  and  background
       modeling  steps, returning to the originally desired header size for the final coaddition.
       The default background matching assumes that there are no non-linear background variations
       in  the  individual  images  (and  therefore  in the overlap differences). If there is any
       uncertainty in this regard, it is safer to turn on the "level  only"  background  matching
       (the "-l" flag in mBgModel.

COPYRIGHT

       2001-2015 California Institute of Technology, Pasadena, California

       If  your  research  uses  Montage,  please  include  the  following acknowledgement: "This
       research made use of Montage. It is funded by the National Science Foundation under  Grant
       Number  ACI-1440620,  and  was  previously  funded  by  the National Aeronautics and Space
       Administration's Earth Science Technology Office, Computation Technologies Project,  under
       Cooperative  Agreement  Number  NCC5-626  between  NASA  and  the  California Institute of
       Technology."

       The Montage distribution includes an adaptation of the MOPEX algorithm  developed  at  the
       Spitzer Science Center.