Match Image Stars with Catalog Stars

WCSTools programs
immatch is a utility for matching stars in a FITS or IRAF image with a world coordinate system (WCS) in its header with stars in a reference catalog. The WCS is the relationship between sky coordinates and image pixels and can be described in a standard way in the header of an image. If there is no WCS in the header, imwcs may be used to set one.

The HST Guide Star Catalog, the USNO UJ Catalog, the USNO A Catalogs, or a user-supplied catalog may be used.

Command Line Arguments

There are two USNO-B1.0-specific parameters which can be set on the command line:
minid=number If the object is found on fewer than this many plates, where the range is 2-5, it is left off the list. All Tycho-2 stars, where the catalog value of this number is set to zero, are included unless number is negated. The default value set in the file libwcs/ubcread.c is 0. For the most accurate positions, use minid=4.
minpmqual=number If the proper motion quality flag is less than this number, proper motion is never added to the catalog position. The range is 1-9 from the catalog, or 10 if the proper motion is from the Tycho-2 Catalog. Setting this to 11 will never add proper motion. The default value set in the file libwcs/ubcread.c is 3. For the best proper motions, use minpmqual=9.


1. Find HST Guide Star Catalog Stars in an image
2. Find USNO-A2.0 catalog stars using SExtractor to find stars in an image

Last updated 10 July 2003 by Doug Mink dmink@cfa.harvard.edu

Telescope Data Center