B seconds past J2000 TDB.


      fixref      is the name of a body-fixed reference frame centered
                  on the target body. `fixref' may be any such frame
                  supported by the SPICE system, including built-in
                  frames (documented in the Frames Required Reading)
                  and frames defined by a loaded frame kernel (FK). The
                  string `fixref' is case-insensitive, and leading and
                  trailing blanks in `fixref' are not significan