NAME

       mBestImage - Determine which image covers a location "best"

SYNOPSIS

       mBestImage [-d level] images.tbl ra dec

DESCRIPTION

       Given  a  list  of  images  and  a  position  on the sky, determine which image covers the
       location "best" (i.e., the one where the position is farthest from the nearest edge).

OPTIONS

       -d debug
              Turn on debugging to the specified level (1 or 2)

ARGUMENTS

       images.tbl
              Input table of image metadata (as generated by mImgtbl).

       ra     RA of location of interest (in degrees)

       dec    Declination of location of interest (in degrees)

RESULT

       [struct stat="OK", file="filename", edgedist=distance]

       or

       [struct stat="OK", file="filename", url="fileurl", edgedist=distance]

       where filename is the name of the  "best"  image  found  in  images.tbl  and  distance  is
       measured  from the point of interest to the nearest edge of the image.  If the input table
       included a URL column, the output message will also include the image's URL.

MESSAGES

       OK     [struct stat="OK", file="filename", url="fileurl", edgedist=distance"]

       OK     [struct stat="OK", file="filename", edgedist=distance"]

       ERROR  Invalid image metadata file: images.tbl

       ERROR  Need columns: cntr and fname; ctype1 ctype2  nl  ns  crval1  crval2  crpix1  crpix2
              cdelt1 cdelt2 and crota2 or cd matrix / ra dec ra1 ... dec4

       ERROR  Bad WCS for image fitsfile

       ERROR  No image covers this position.

EXAMPLES

       Given a table of image metadata describing images covering a 0.5 by 0.5 degree area around
       m31 (2mass_m31_j.tbl), narrow it down to the image which includes the best coverage of one
       particular location:

       mBestImage 2mass_m31_j.tbl 10.7 41.2
              [struct stat="OK", file="2mass-atlas-971024n-j0080033.fits", edgedist=0.008436]

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.