at photons
                             emitted from the observer's location must
                             be &quot;aimed&quot; to hit the target.

                  &quot;XCN&quot;      &quot;Transmission&quot; case: converged  
                             Newtonian light time correction. 
 
                  &quot;XCN+S&quot;    &quot;Transmission&quot; case: converged Newtonian
                             light time correction and stellar
                             aberration correction.
 
 
    