slaDs2tp -

SYNOPSYS

PARAMETERS

double ra

double dec

double raz

double decz

double *xi

double *eta

int *j

DESCRIPTION

  Projection of spherical coordinates onto tangent plane
  ('gnomonic' projection - 'standard coordinates').

  (double precision)

Given

     ra,dec      double   spherical coordinates of point to be projected
     raz,decz    double   spherical coordinates of tangent point

Returned

     *xi,*eta    double   rectangular coordinates on tangent plane
     *j          int      status:   0 = OK, star on tangent plane
                                    1 = error, star too far from axis
                                    2 = error, antistar too far from axis
                                    3 = error, antistar on tangent plane

  P.T.Wallace   Starlink   31 October 1993

SEE ALSO

• slalib.3