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

The FITS data format is widely used within the international astronomical community, from the radio to gamma-ray regimes, for data interchange and archive, and also increasingly as an online format. It is described in

"Definition of The Flexible Image Transport System (FITS)", FITS Standard, Version 3.0, 2008 July 10.

available from the FITS Support Office at http://fits.gsfc.nasa.gov.

The FITS WCS standard is described in

"Representations of world coordinates in FITS" (Paper I), Greisen, E.W., & Calabretta, M.R. 2002, A&A, 395, 1061-1075
"Representations of celestial coordinates in FITS" (Paper II), Calabretta, M.R., & Greisen, E.W. 2002, A&A, 395, 1077-1122
"Representations of spectral coordinates in FITS" (Paper III), Greisen, E.W., Calabretta, M.R., Valdes, F.G., & Allen, S.L. 2006, A&A, 446, 747
"Representations of distortions in FITS world coordinate systems", Calabretta, M.R. et al. (WCS Paper IV, draft dated 2004/04/22), available from http://www.atnf.csiro.au/people/Mark.Calabretta
"Mapping on the HEALPix Grid" (HPX, Paper V), Calabretta, M.R., & Roukema, B.F. 2007, MNRAS, 381, 865
"Representing the 'Butterfly' Projection in FITS: Projection Code XPH" (XPH, Paper VI), Calabretta, M.R., & Lowe, S.R. 2013, PASA, 30, e050
"Representations of time coordinates in FITS: Time and relative dimension in space" (Paper VII), Rots, A.H., Bunclark, P.S., Calabretta, M.R., Allen, S.L., Manchester R.N., & Thompson, W.T. 2015, A&A, 574, A36

Reprints of all published papers may be obtained from NASA's Astrophysics Data System (ADS), http://adsabs.harvard.edu/. Reprints of Papers I, II (including HPX & XPH), and III are available from http://www.atnf.csiro.au/people/Mark.Calabretta. This site also includes errata and supplementary material for Papers I, II and III.

Additional information on all aspects of FITS and its various software implementations may be found at the FITS Support Office http://fits.gsfc.nasa.gov.