source: trunk/MagicSoft/slalib/galsup.c

#include "slalib.h"
#include "slamac.h"
void slaGalsup ( double dl, double db, double *dsl, double *dsb )
/*
**  - - - - - - - - - -
**   s l a G a l s u p
**  - - - - - - - - - -
**
**  Transformation from IAU 1958 Galactic coordinates to
**  De Vaucouleurs supergalactic coordinates.
**
**  (double precision)
**
**  Given:
**     dl,db       double       Galactic longitude and latitude l2,b2
**
**  Returned:
**     *dsl,*dsb   double       Supergalactic longitude and latitude
**
**  (all arguments are radians)
**
**  Called:
**     slaDcs2c, slaDmxv, slaDcc2s, slaDranrm, slaDrange
**
**  References:
**
**     De Vaucouleurs, De Vaucouleurs, & Corwin, Second reference
**     catalogue of bright galaxies, U. Texas, page 8.
**
**     Systems & Applied Sciences Corp., Documentation for the
**     machine-readable version of the above catalogue,
**     contract NAS 5-26490.
**
**    (These two references give different values for the Galactic
**     longitude of the Supergalactic origin.  Both are wrong;  the
**     correct value is l2 = 137.37.)
**
**  Last revision:   25 January 1999
**
**  Copyright P.T.Wallace.  All rights reserved.
*/
{
   double v1[3], v2[3];

/*
**  System of Supergalactic coordinates:
**
**    SGl   SGb        l2     b2      (deg)
**     -    +90      47.37  +6.32
**     0     0         -      0
**
**  Galactic to Supergalactic rotation matrix:
*/
   static double rmat[3][3] =
   {
      { -0.735742574804,  0.677261296414,  0.0            },
      { -0.074553778365, -0.080991471307,  0.993922590400 },
      {  0.673145302109,  0.731271165817,  0.110081262225 }
   };

/* Spherical to Cartesian */
   slaDcs2c ( dl, db, v1 );

/* Galactic to Supergalactic */
   slaDmxv ( rmat, v1, v2 );

/* Cartesian to spherical */
   slaDcc2s ( v2, dsl, dsb );

/* Express in conventional ranges */
   *dsl = slaDranrm ( *dsl );
   *dsb = slaDrange ( *dsb );
}