Re: DS9, etc.

[<aah@nofs.navy.mil>]

Any normal image-processing program will allow you
to extract a subimage; DS9 is just an image viewer
as noted before.
  If you want to do it under iraf, the appropriate
command is imcopy, which will permit copying of
any image subsection from a command line.  For example,

imcopy input_image[40:70,300:400] output_image

will create an image "output_image.fits", and
copy columns 40 through 70 and rows 300 through 400
of image "input_image.fits" into the new image.
The new image will have size 31x101.
You can do this with wildcards, with input file
lists, etc. for multiple files.
Read the tutorial "A Beginner's Guide to Using
IRAF" by Jeanette Barnes, on the NOAO/IRAF web site.
IRAF is not that user-unfriendly; learning any new
system takes some time.  The area of contention is
GUI vs. command-line, and that is a philosophical
argument that should not be viewed as a strike
against any system.
Arne