.TH MBESTIMAGE 1 "Dec 2016" "Montage 5" "Montage"
.SH NAME
mBestImage \- Determine which image covers a location "best"

.SH SYNOPSIS
mBestImage [\-d \fIlevel\fP] images.tbl ra dec

.SH 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).

.SH OPTIONS
.TP
\-d \fIdebug\fP
Turn on debugging to the specified level (1 or 2)

.SH ARGUMENTS
.TP
images.tbl
Input table of image metadata (as generated by \fBmImgtbl\fP).
.TP
ra
RA of location of interest (in degrees)

.TP
dec
Declination of location of interest (in degrees)


.SH RESULT
\fB[struct stat="OK", file="\fIfilename\fP", edgedist=\fIdistance\fP]

\fIor\fP

\fB[struct stat="OK", file="\fIfilename\fP", url="\fIfileurl\fP", edgedist=\fIdistance\fP]\fP\fP
.PP
where \fIfilename\fP is the name of the "best" image found in \fIimages.tbl\fP and \fIdistance\fP 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.

.SH MESSAGES
.TP
OK
[struct stat="OK", file="\fIfilename\fP", url="\fIfileurl\fP", edgedist=\fIdistance\fP"]
.TP
OK
[struct stat="OK", file="\fIfilename\fP", edgedist=\fIdistance\fP"]
.TP
ERROR
Invalid image metadata file: \fIimages.tbl\fP
.TP
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
.TP
ERROR
Bad WCS for image \fIfitsfile\fP
.TP
ERROR
No image covers this position.

.SH EXAMPLES
.PP
Given a table of image metadata describing images covering a 0.5 by 0.5 degree area around m31 (\fB2mass_m31_j.tbl\fP), narrow it down to the image which includes the best coverage of one particular location:
.TP
mBestImage 2mass_m31_j.tbl 10.7 41.2
[struct stat="OK", file="2mass-atlas-971024n-j0080033.fits", edgedist=0.008436]

.SH BUGS
The drizzle algorithm has been implemented but has not been tested
in this release.
.PP
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"]
.PP
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.

.SH COPYRIGHT
2001-2015 California Institute of Technology, Pasadena, California
.PP
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."
.PP
The Montage distribution includes an adaptation of the MOPEX algorithm
developed at the Spitzer Science Center.