NAME

       mTileHdr - Create a set of tiled images or header templates from a FITS file or header

SYNOPSIS

       mTileHdr [-d] [-s statusfile] orig.hdr new.hdr nx ny ix iy [xpad [ypad]]

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.

       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.

OPTIONS

       -d     Turns on debugging.

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

ARGUMENTS

       orig.hdr
              ASCII header template from which to derive tiled headers

       new.hdr
              Path to output header

       nx     Number of tiles in the x-direction

       ny     Number of tiles in the y-direction

       ix     Integer identifying the x location of the output tile on the grid (counting from 0)

       iy     Integer identifying the y location of the output tile on the grid (counting from 0)

       xpad   Number of pixels to overlap tiles in the x direction (optional; default is 0)

       ypad   Number of pixels to overlap tiles in the y direction (optional; default is 0)

RESULT

       [struct stat="OK", naxis1=xsize, naxis1=ysize, crpix1=xref, crpix2=yref]

       Where xsize and ysize are the x and y dimensions of the  image  described  by  the  output
       header,  and crpix1 and crpix2 are the new offset from the original reference pixel on the
       sky.

MESSAGES

       OK     [struct stat="OK", naxis1=xsize, naxis2=ysize, crpix1=xref, crpix2=yref]

       ERROR  Cannot open status file: statusfile

       ERROR  (nx,ny) have to be positive integers and (ix,iy) have to be in the range  (0..nx-1,
              0..ny-1)

       ERROR  Cannot open output template new.hdr

       ERROR  Bad template:orig.hdr

       ERROR  Bad template:new.hdr

       ERROR  Output wcsinit() failed.

EXAMPLES

       template.hdr is 850x850 pixels, and we want to generate the center tile out of 9 (3 by 3):

       $ mTileHdr template.hdr tile_1_1.hdr 3 3 1 1
              [struct stat="OK", naxis1=283, naxis2=283, crpix1=-283, crpix2=-283]

       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).

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.