Representations of world coordinates in FITS, Greisen, E.W. & Calabretta, M.R., 2002, Astronomy & Astrophysics, 395, 1061-1075.

Also a supplement to Paper I entitled Concatenation of FITS World Coordinate Systems by Steve Allen and Jessica Mink.

Representations of celestial coordinates in FITS, Calabretta, M.R., & Greisen, E.W., 2002, Astronomy & Astrophysics, 395, 1077-1122.

Miscellaneous notes on the derivation of some formulae and special conditions in Paper II, dated 2004-02-11.  

Representations of spectral coordinates in FITS, Greisen, E.W., Calabretta, M.R. Valdes, F.G., & Allen, S.L., 2006, Astronomy & Astrophysics, 446, 747-771.

Errata dated 2013-09-21 for Papers I, II & III.

Representations of distortions in FITS world coordinate systems, Calabretta et al., draft dated 2004-04-22.

Mapping on the HEALPix grid, Calabretta M.R. & Roukema B.F. 2007, Monthly Notices of the Royal Astronomical Society, 381, 865-872. Describes the HEALPix projection and introduces the HPX projection type in FITS.

This diagram illustrating Bonne's projection with conformal latitude +35° was produced by WCSLIB, a C implementation of the coordinate transformations defined in the FITS WCS papers. The non-oblique native graticule is in dark green.

The oblique 15° celestial graticule centred on celestial coordinates (0°, +45°) with north celestial pole at native coordinates (45°, 0°) is colour-coded blue, red and white (in increasing order) with the equator and prime meridian in yellow.

Representing the 'Butterfly' Projection in FITS — Projection Code XPH, Calabretta M.R. & Lowe S.R. 2013, Publications of the Astronomical Society of Australia, 30, e050.

Representations of time coordinates in FITS - Time and relative dimension in space, Rots, A.H., Bunclark, P.S., Calabretta, M.R., Allen, S.L., Manchester, R.N., & Thompson, W.T., 2015, Astronomy & Astrophysics, 574, A36.

Introduction to celestial coordinate systems; slides (in HTML) from a talk explaining FITS world coordinate systems.

WCSLIB is implemented in C, with support for FORTRAN via a set of wrapper functions. A doxygen-generated programming manual (HTML and PDF) is provided.

NEW! (2025-12-06) WCSLIB 8.5 contains a number of enhancements and bug fixes. All older releases of WCSLIB are also available.

As of release 8.5, WCSLIB's RCS version files are now included in the distribution, thereby providing a documented history of all changes made since v1.0.

WCSLIB was honoured with the ADASS software prize for 2025 for which I gave the invited conference talk remotely by video.

A general curvilinear axis drawing routine, PGSBOX, for PGPLOT that can optionally interface to WCSLIB, is also included with WCSLIB.

Utility program HPXcvt is included with WCSLIB. It converts 1D HEALPix pixelization data stored in a variety of forms in FITS, including ring or nested organization in a binary table extension, into a 2D primary image array with HPX or XPH coordinate representation.

An example (13MiB bzip'd) is provided of its application to the WMAP 3-year Internal Linear Combination map.

Example FITS files produced for each of the projections in Paper II and for a selection of spectral representations from Paper III, are available for testing purposes.