The apparent position of the Moon with respect to the object, expressed in Cartesian components, as a function of time. The light time delay is actually computed between the Moon and the object's central body, rather than directly from the object itself. The apparent position can be requested in a variety of coordinate systems. The available coordinate systems depend on the object's central body. Nominally, the systems Fixed, Inertial, J2000, TrueOfDate, and MeanOfDate are supported, although some central bodies (notably the Earth and Sun) have more. The following lists the systems available for Earth.