berration corrections, when used, are applied as follows: 
 
 
      Observer-target body vector 
      --------------------------- 
 
      In addition to light time correction, stellar aberration is used
      in computing the apparent target surface point position as seen
      from the observer's location at time `et'. This apparent position
      defines the observer-target surface point vector.
 
 
      Target body-Sun vector 
      ---------------------- 
 
      The target body-Sun vector is the ap