- NAME
PRECESS_XYZ
- PURPOSE
Precess equatorial geocentric rectangular coordinates.
- CALLING SEQUENCE
precess_xyz, x, y, z, equinox1, equinox2
- INPUT/OUTPUT
x,y,z: scalars or vectors giving heliocentric rectangular coordinates
THESE ARE CHANGED UPON RETURNING.
- INPUT
EQUINOX1: equinox of input coordinates, numeric scalar
QUINOX2: equinox of output coordinates, numeric scalar
- OUTPUT
x,y,z are changed upon return
- NOTES
The equatorial geocentric rectangular coords are converted
to RA and Dec, precessed in the normal way, then changed
back to x, y and z using unit vectors.
- XAMPLE
Precess 1950 equinox coords x, y and z to 2000.
IDL> precess_xyz,x,y,z, 1950, 2000
- ISTORY
Written by P. Plait/ACC March 24 1999
(unit vectors provided by D. Lindler)
se /Radian call to PRECESS W. Landsman November 2000
se two parameter call to ATAN W. Landsman June 2001