I: "Representations of world coordinates in FITS", Greisen, E.W. & Calabretta, M.R. (2002), Astronomy & Astrophysics, 395, 1061-1075.   (gzip'd PostScript version)

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

II: "Representations of celestial coordinates in FITS", Calabretta. M.R., & Greisen, E.W., (2002), Astronomy & Astrophysics, 395, 1077-1122.   (gzip'd PostScript version)

III: "Representations of spectral coordinates in FITS", Greisen, E.W., Calabretta, M.R. Valdes, F.G., & Allen, S.L., (2006), Astronomy & Astrophysics, 446, 747-771.   (gzip'd PostScript version)

IV: "Representations of distortions in FITS world coordinate systems", Calabretta, Valdes, Greisen, & Allen, draft dated 2004/04/22.   (PDF version)

Miscellaneous notes on the derivation of some formulae and special conditions in Paper II, dated 2004/02/11.   (PDF version)

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.

Errata dated 2007/12/22 for Papers I, II & III.   (PDF version)

"Mapping on the HEALPix grid", Calabretta & Roukema, as accepted by Monthly Notices of the Royal Astronomical Society (MNRAS) on 2007/07/25, introduces the HPX projection type. (gzip'd PostScript version)

The official refereed version of the paper was published as MNRAS 381 865, and can be accessed from ADS .

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