o
         use light time alone.


      2) Find the corrected pointing direction to radiate a signal
         to a target. This computation is often applicable for
         implementing communications sessions.

            Use 'XLT+S' or 'XCN+S: apply both light time and stellar
            aberration corrections for transmission.


      3) Compute the apparent position of a target body relative
         to a star or other distant object.

            Use 'LT', 'CN', 'LT+S', or 'CN+S' as needed to match 