| Name | Description |
|---|---|
| Fixed | A coordinate system attached to the central body and rotating with it. The z-axis is nominally along the rotation axis. |
| ICRF | The relative ephemeris of the assigned object with respect to the primary object, expressed in Cartesian components, as a function of time. The relative velocity vector is computed as observed in the requested coordinate system, and expressed in components of that frame. The relative ephemeris 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. |
| MeanOfDate | The mean equator mean equinox coordinate system evaluated at the requested time. |
| MeanOfEpoch | The mean equator mean equinox coordinate system evaluated at the epoch of the object. |
| TrueOfDate | The true equator true equinox coordinate system evaluated at the requested time. |
| TrueOfEpoch | The true equator true equinox coordinate system evaluated at the epoch of the object. |
| B1950 | The mean equator mean equinox coordinate system evaluated at the beginning of the Besselian year 1950 (31 December 1949 22:09:46.866 = JD 2433282.4234591). |
| TEMEOfEpoch | The true equator mean equinox coordinate system evaluated at the epoch of the object. |
| TEMEOfDate | The true equator mean equinox coordinate system evaluated at the requested time. |
| AlignmentAtEpoch | The non-rotating coordinate system coincident with the Fixed system evaluated at the object's coordinate reference epoch. |
| J2000 | The mean equator mean equinox coordinate system evaluated at the J2000.0 epoch (2000 January 1.5 = JD 2451545.0 TDB). |
STK Programming Interface 11.0.1