NAME:
galcenrect_to_vxvyvz
PURPOSE:
transform rectangular Galactocentric coordinates to XYZ coordinates (wrt Sun) for velocities
INPUT:
vXg - Galactocentric x-velocity
vYg - Galactocentric y-velocity
vZg - Galactocentric z-velocity
vsun - velocity of the sun ndarray[3]
OUTPUT:
[:,3]= vx, vy, vz
HISTORY:
2011-02-24 - Written - Bovy (NYU)