imwub1 is an alias for imwcs,
a program which sets the
world coordinate system (WCS)
of a FITS or IRAF image. 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. The program was
originally written at the University of Iowa, but has been adapted and
amplified by Doug Mink at the Smithsonian Astrophysical Observatory.
Image World Coordinate Setting Program
imwub1 uses the US Naval
Observatory B1.0 catalog, which contains 1,036,366,767 stars,
which should provide a good number of reference stars for any image.
There are two USNO-B1.0-specific parameters which can be set on the command
line. If they appear, they must come after -c ub1 or imwub1
on the command line.
||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.
||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.