.TH MTILEHDR 1 "Dec 2016" "Montage 5" "Montage"
.SH NAME
mTileHdr \- Create a set of tiled images or header templates from a FITS file or header

.SH SYNOPSIS
mTileHdr [\-d] [\-s \fIstatusfile\fP] orig.hdr new.hdr nx ny ix iy [xpad [ypad]]

.SH DESCRIPTION
Takes a header template file and creates another which represents one of a regular set of tiles covering the original.  The user specifies the tile gridding and which tile is desired.
.PP
Only the NAXIS and CRVAL keyword lines are changed (pixel size and reference point location); all other keyword values will be inherited from the input header.

.SH OPTIONS
.TP
\-d
Turns on debugging.
.TP
\-s \fIstatusfile\fP
Output and errors are sent to \fIstatusfile\fP instead of to stdout

.SH ARGUMENTS
.TP
orig.hdr
ASCII header template from which to derive tiled headers
.TP
new.hdr
Path to output header
.TP
nx
Number of tiles in the x-direction
.TP
ny
Number of tiles in the y-direction
.TP
ix
Integer identifying the x location of the output tile on the grid (counting from 0)
.TP
iy
Integer identifying the y location of the output tile on the grid (counting from 0)
.TP
xpad
Number of pixels to overlap tiles in the x direction (optional; default is 0)
.TP
ypad
Number of pixels to overlap tiles in the y direction (optional; default is 0)

.SH RESULT
\fB[struct stat="OK", naxis1=\fIxsize\fP, naxis1=\fIysize\fP, crpix1=\fIxref\fP, crpix2=\fIyref\fP]\fP
.PP
Where \fIxsize\fP and \fIysize\fP are the x and y dimensions of the image described by the output header, and \fIcrpix1\fP and \fIcrpix2\fP are the new offset from the original reference pixel on the sky.

.SH MESSAGES
.TP
OK
[struct stat="OK", naxis1=\fIxsize\fP, naxis2=\fIysize\fP, crpix1=\fIxref\fP, crpix2=\fIyref\fP]
.TP
ERROR
Cannot open status file: \fIstatusfile\fP
.TP
ERROR
(nx,ny) have to be positive integers and (ix,iy) have to be in the range (0..nx-1, 0..ny-1)
.TP
ERROR
Cannot open output template \fInew.hdr\fP
.TP
ERROR
Bad template:\fIorig.hdr\fP
.TP
ERROR
Bad template:\fInew.hdr\fP
.TP
ERROR
Output wcsinit() failed.

.SH EXAMPLES
.PP
template.hdr is 850x850 pixels, and we want to generate the center tile out of 9 (3 by 3):
.TP
$ mTileHdr template.hdr tile_1_1.hdr 3 3 1 1
[struct stat="OK", naxis1=283, naxis2=283, crpix1=\-283, crpix2=\-283]
.PP
tile_1_1.hdr has the same reference location and pixel scale as the input header, but a new pixel offset (CRPIX) and size (NAXIS).

.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.