void radrec_c ( SpiceDouble range,
SpiceDouble ra,
SpiceDouble dec,
SpiceDouble rectan[3] )
Convert from range, right ascension, and declination to rectangular
coordinates.
None.
CONVERSION, COORDINATES
VARIABLE I/O DESCRIPTION
  
range I Distance of a point from the origin.
ra I Right ascension of point in radians.
dec I Declination of point in radians.
rectan O Rectangular coordinates of the point.
range is the distance of the point from the origin. Output
units are the same as the units associated with `range.'
ra is the right ascension of the input point: the angular
distance measured toward the east from the prime meridian
to the meridian containing the input point. The direction
of increasing right ascension is from the +X axis towards
the +Y axis.
The range (i.e., the set of allowed values) of
`ra' is unrestricted. Units are radians.
dec is the declination of the point. This is the angular
distance from the XY plane to the point.
The range of `dec' is unrestricted. Units are radians.
rectan is the array containing the rectangular coordinates of
the point. The output units associated with `rectan'
are those associated with the input `range.'
None.
Error free.
None.
None.
The following code fragment converts right ascension and
declination from the B1950 reference frame to the J2000 frame.
#include "SpiceUsr.h"
SpiceDouble ra;
SpiceDouble dec;
SpiceDouble r;
SpiceDouble rotab [ 3 ][ 3 ];
SpiceDouble oldvec [ 3 ];
SpiceDouble newvec [ 3 ];
radrec_c ( 1.0, ra, dec, oldvec );
pxform_c ( "B1950", "J2000", 0.0, rotab );
mxv_c ( rotab, oldvec, newvec );
recrad_c ( newvec, &r, &ra, &dec );
None.
"Celestial Mechanics, A Computational Guide for the Practitioner"
by Laurence G. Taff
N.J. Bachman (JPL)
H.A. Neilan (JPL)
E.D. Wright (JPL)
CSPICE Version 1.0.2, 28JUL2003 (NJB)
Various header corrections were made.
CSPICE Version 1.0.1, 13APR2000 (NJB)
Made some minor updates and corrections in the code example.
CSPICE Version 1.0.0, 08FEB1998 (EDW)
range ra and dec to rectangular coordinates
right_ascension and declination to rectangular
