parent position of the Sun, 
      corrected for light time and stellar aberration, as seen from 
      the target body at time et-lt.  Note that the target body's 
      position is not affected by the stellar aberration correction 
      applied in finding its apparent position as seen by the 
      observer. 
  
   Once all of the vectors, as well as the target body's orientation,
   have been computed with the proper aberration corrections, the
   element of time is eliminated from the computation. The 