                  iterative solution of the light time 
                             equation (see Particulars for details). 
                             The solution invoked by the &quot;LT&quot; option 
                             uses one iteration. 
 
                  &quot;LT+S&quot;     Correct for one-way light time and stellar
                             aberration using a Newtonian formulation.
                             This option modifies the positions
                             obtained