   The light time corrected position vector is
 
         T(et-lt) - O(et) 
  
      If correction for stellar aberration is requested, the target 
      position is rotated toward the solar system 
      barycenter-relative velocity vector of the observer.  The 
      rotation is computed as follows: 
 
         Let r be the light time corrected vector from the observer 
         to the object, and v be the velocity of the observer with 
         respect to the solar system barycenter. Let w be the angle 
