NAME

       mSubset  -  Filter  an  image metadata table down to those records representing FITS files
       that overlap a footprint on the sky

SYNOPSIS

       mSubset [-d level] [-f] [-s statusfile] images.tbl template.hdr subset.tbl

DESCRIPTION

       Generates a table of images that is a subset of the input  table,  containing  only  those
       images that cover the area defined by a given FITS header.

OPTIONS

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

       -f     Fast  mode  -  input file must include corners (-c flag in mImgtbl) to utilize this
              mode.

       -s statusfile
              Output and errors are sent to statusfile instead of to stdout

ARGUMENTS

       images.tbl
              ASCII table (generated by mImgtbl) containing metadata for image collection.

       template.hdr
              FITS header template defining the area of interest.

       subset.tbl
              Path to output table, which will contain only those FITS images covering  the  area
              defined by template.hdr.

RESULT

       [struct stat="OK", count=nin, nmatches=nout]

       where nin is the number of rows found in images.tbl, and nmatches is the number of rows in
       subset.tbl,  which  includes  only  those  images  that  overlap  the  area   defined   by
       template.hdr.

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.