WCS_ROTATE

       Rotate between standard (e.g. celestial) and native coordinates

       Computes a spherical coordinate rotation between native coordinates
       and  standard celestial coordinate system (celestial, Galactic, or
       ecliptic).   Applies the equations in Appendix A of the paper
       "Representation of Celestial Coordinates in FITS" by Calabretta
       Greisen (2002, A&A, 395, 1077).    Also see
       http://www.aoc.nrao.edu/~egreisen

       Mapping and Auxiliary FITS Routine

       WCS_ROTATE, longitude, latitude, phi, theta, crval,
               [LONGPOLE = , LATPOLE = , /REVERSE, /ORIGIN ]

       crval - 2 element vector containing standard system coordinates (the
               longitude and latitude) of the reference point

       longitude - longitude of data, scalar or vector, in degrees, in the
               standard celestial coordinate system
       latitude - latitude of data, same number of elements as longitude,
               in degrees
       phi - longitude of data in the native system, in degrees, scalar or
               vector
       theta - latitude of data in the native system, in degrees, scalar or
               vector
       If the keyword(REVERSE) is set then phi and theta are input parameters
       and longitude and latitude are computed.    Otherwise, longitude and
       latitude are input parameters and phi and theta are computed.

      ORIGIN - If this keyword is set and non-zero, then the reference point
               given by CRVAL in the native system is assumed to be at the
               origin of the coordinates, rather than at the North Pole.
               ORIGIN should be set for cylindrical projections (Cylindrical
               perspective-CYP, Cartesian - CAR, Mercator - MER, Cylindrical
               Equal area - CEA) and conventional projections (Bonne's equal
               area - BON, Polyconic - PCO, Sinusoidal - GLS, Parabolic - PAR,
               Aitoff - AIT, Mollweide - MOL, COBE quadrilateralized sphere -
               CSC, Quadrilateralized Spherical Cube - QSC, and Tangential
               Spherical Cube - TSC)
       LONGPOLE - native longitude of standard system's North Pole, default
               for a Zenithal system is 180 degrees
       LATPOLE -  native latitude of the standard system's North Pole
       /REVERSE - if set then phi and theta are input parameters and longitude
                  and latitude are computed.    By default, longitude and
                  latitude are input parameters and phi and theta are computed.

       Written    W. Landsman               December, 1994
       Fixed error in finding North Pole if /ORIGIN and LONGPOLE NE 180
       Xiaoyi Wu and W. Landsman,   March, 1996
       Fixed implementation of March 96 error, J. Thieler,  April 1996
       Updated to IDL V5.0   W. Landsman    December 1997
       Fixed determination of alpha_p if /ORIGIN and LONGPOLE EQ 180
               W. Landsman    May 1998
       Ensure argument of ASIN() is -1


Last modified by pro2html on 2004 May 07 at 03:43 UTC


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