man mShrinkHdr (1): Make a FITS header from a template with different pixel scale

SYNOPSIS

mShrinkHdr [-d][-s scale] template.hdr shrunken.hdr

DESCRIPTION

  There are two ways to generate "thumbnail" images.  One is to build a full-resolution mosaic
  and shrink it down using mShrink to the scale desired.  This process can be costly if the
  full resolution image is not desired (or not desired yet).  It is much faster to mosaic at
  the scale of the thumbnail itself.  One reason for doing this could be to evaluate whether
  th full-resolution mosaic is worth building at all.

  mShrinkHdr is a simple utility that takes a FITS header template (such as might come out of
  mMakeHdr or mHdr) and make a new one at a differenc pixel scale.  The default scale for this
  new header is 200 pixels, though the user can override this with any value.

OPTIONS

-d

Turn on debugging.

-s scale

Set the size in pixels of the larger axis.

ARGUMENTS

template.hdr

Original FITS header template.

shrunken.hdr

"Thumbnail" FITS header template.

RESULT

  If successful, the result is a new FITS header template with a size and
  pixel scale appropriate to making a thumbnail mosaic.

MESSAGES

ERROR: Cannot open output template file
ERROR: Bad template: filename
ERROR: Output wcsinit() failed.

EXAMPLES

$ mShrinkHdr region.hdr thumbnail.hdr: [struct stat="OK"]

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.