 Proposed FITS Standard World Coordinate Systems

Twentyfive projections are supported by the FITS WCS standard, which
is documented by
Eric Greisen and Mark Calabretta
and implemented in Mark's
WCSLIB software library.
A twentysixth, NCP, which is supported by
classic AIPS software
is computed using the worldpos and worldpix subroutines
written by Bill Cotton and Eric Greisen of NRAO. That original source
code is available at the
NRAO FITS WCS site.
The FITS data format is best described by the current FITS standard,
NOST 1002.0 available from the
NASA FITS Support Office
as a
597K uncompressed Postscript,
239K gzcompressed Postscript, or
386K PDF
file.
Steve Allen and Doug Mink proposed a method of specifying dependent
WCS projections in an unpublished appendix to Calabretta and Griesen's
paper, available in PDF
and Postscript.
Projections included in WCSLIB are
 AZP: Zenithal (Azimuthal) Perspective
 SZP: Slant Zenithal Perspective
 TAN: Gnomonic = Tangent Plane
 SIN: Orthographic/synthesis
 STG: Stereographic
 ARC: Zenithal/azimuthal equidistant
 ZPN: Zenithal/azimuthal PolyNomial
 ZEA: Zenithal/azimuthal Equal Area
 AIR: Airy
 CYP: CYlindrical Perspective
 CAR: Cartesian
 MER: Mercator
 CEA: Cylindrical Equal Area
 COP: COnic Perspective
 COD: COnic equiDistant
 COE: COnic Equal area
 COO: COnic Orthomorphic
 BON: Bonne
 PCO: Polyconic
 SFL: SansonFlamsteed
 PAR: Parabolic
 AIT: HammerAitoff equal area allsky
 MOL: Mollweide
 CSC: COBE quadrilateralized Spherical Cube
 QSC: Quadrilateralized Spherical Cube
 TSC: Tangential Spherical Cube
 NCP: North celestial pole (special case of SIN)
 GLS: GLobal Sinusoidal (Similar to SFL)
WCSTools versions 2.9 and later implement the use of multiple world
coordinate systems, with the WCS to which a keyword applies designated
by an appended character.
Thus CTYPE1 applies to the default WCS, which may be named using
WCSNAME. A second WCS would use keywords such as CTYPE1A
and WCSNAMEA. An additional nonstandard feature has been added,
the keyword WCSDEPx, which is set equal to the name of a WCS
which would be found in a WCSNAMEx keyword value or a single
character which is assumed to be the suffix for the WCS
Last updated 19 May 2014 by
Jessica Mink
[WCSTools WCS]
[SAOimage WCS]