Data Provider Groups | Data Provider Elements

Classical Elements

Classical osculating orbital elements, sometimes referred to as Keplerian elements, computed using ephemeris with respect to the object's central body, as observed from the requested coordinate system, as a function of time.

Available for these objects: LaunchVehicle, Missile, 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
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.
Semi-major Axis	Distance	Real Number	A measure of the size of the orbit. Orbits with eccentricity <1 are ellipses, with major and minor axes identifying the symmetry axes of the ellipse, the major axis being the longer one. The value is half the length of the major axis.
Eccentricity	Unitless	Real Number	A measure of the shape of the orbit. Values <1 indicate an ellipse (where zero is a circular orbit) and values >1 indicate a hyperbola.
Inclination	Angle	Real Number or Text	The angle between the orbit plane and the XY plane of the coordinate system.
RAAN	Longitude	Real Number or Text	The angle in the XY plane from the X axis to the ascending node, measured in a right-handed sense about the Z axis. in the equatorial plane. For equatorial orbits, the ascending node is defined to be directed along the positive X axis, and thus the value is 0.0.
Arg of Perigee	Angle	Real Number or Text	The angle from the ascending node to the periapsis vector measured in the orbit plane in the direction of the object's motion. The periapsis vector locates the closest point of the orbit. For a circular orbit, the value is defined to be zero (i.e., periapsis at the ascending node).
True Anomaly	Angle	Real Number or Text	The angle from the periapsis vector, measured in the orbit plane in the direction of motion, to the position vector.
Mean Anomaly	Angle	Real Number or Text	A measure of the time past periapsis passing, expressed as an angle.
Arg of Latitude	Angle	Real Number or Text	The sum of the true anomaly and the argument of periapsis..
Apogee Altitude	Distance	Real Number	The difference between the radius of apoapsis and the central body's equatorial radius.
Apogee Radius	Distance	Real Number	The magnitude of the apoapsis vector. The apoapsis vector (defined only when the eccentricity is <1) locates the position in the orbit furthest from the central body.
Perigee Altitude	Distance	Real Number	The difference between the radius of periapsis and the central body's equatorial radius.
Perigee Radius	Distance	Real Number	The magnitude of the periapsis vector. The periapsis vector locates the position in the orbit closest to the central body.
Mean Motion (Revs/Day)	Unitless	Real Number	A measure of the osculating period of the orbit, expressed as an angular rate. The value is 2pi rad / orbit_period. Expressed as revolutions per day.
Lon Ascn Node	Longitude	Real Number or Text	A measure of the right ascension of the ascending node, made in the Fixed frame. The value is the detic longitude of the orbit's ascending node. The ascending node crossing is assumed to be at, or prior to, the current position in the orbit in the same nodal revolution.
Eccentric Anomaly	Angle	Real Number or Text	An angle used for converting between true and mean anomaly. Has a geometrical definition as the angle between the line of apsides and a line running from the center of the ellipse to a point Q on a circle circumscribed about the ellipse. The point Q is a projection of the satellite along a line parallel to the minor axis of the ellipse.
Time Past AN	Time	Real Number	The elapsed time since passing the last ascending node crossing based on assumed two-body motion..
Time Past Perigee	Time	Real Number	The elapsed time since passing the last periapsis crossing based on assumed two-body motion..
Period	Time	Real Number	The time to complete an entire cycle.
Longitude of Perigee	Longitude	Real Number or Text	The sum of the right ascension of the ascending node and the argument of periapsis.
Mean Longitude	Longitude	Real Number or Text	Mean longitude is the sum: right_ascension_of_the_ascending_node + argument_of_periapse + mean_anomaly. A measure of the location within the orbit.