"WCSLIB is a C library, supplied with a full set of Fortran wrappers, that
 implements the "World Coordinate System" (WCS) convention in FITS (Flexible
 Image Transport System).  It also includes a PGPLOT-based routine, PGSBOX,
 for drawing general curvilinear coordinate graticules and a number of
 utility programs." - from README file.

WWW: http://www.atnf.csiro.au/people/mcalabre/WCS/index.html