Cartesian Velocity Variants | Data Provider Groups | Data Provider Elements

Cartesian Velocity

The velocity of the object with respect to the object's central body, as observed from the requested coordinate system, expressed in Cartesian components of that system, as a function of time.

Data Provider Variant: Satellite

Available for these objects: Satellite

Type: Time-varying data.

Availability: Reports | Graphs | Dynamic Displays | Strip Charts

Data Provider Groups

Data can be requested in a variety of coordinate systems, where the origin of the coordinate system is the object's central body. 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.

Name	Description
TrueOfDateRotating	A variation of the Fixed system where pole wander is ignored. The equator is the same as the TrueOfDate equator and the frame spins about the TrueOfDate z-axis.
Fixed	A coordinate system attached to the central body and rotating with it. The z-axis is nominally along the rotation axis.
ICRF	International Celestial Reference Frame. The ICRF axes are defined as the inertial (i.e., kinematically non-rotating) axes associated with a general relativity frame centered at the solar system barycenter (often called the BCRF).
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 nonrotating 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 TDB = JD 2451545.0 TDB).

Data Provider Elements

Name	Dimension	Type	Description
Time	Date	Real Number or Text	Time.
x	Rate	Real Number	The X component of the velocity vector.
y	Rate	Real Number	The Y component of the velocity vector.
z	Rate	Real Number	The Z component of the velocity vector.
speed	Rate	Real Number	The magnitude of the velocity vector.
radial	Rate	Real Number	The radial component of the velocity vector.
in-track	Rate	Real Number	The in-track component of the velocity vector (i.e., the component in the orbit plane perpendicular to the radial).