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).
Name |
Dimension |
Type |
Description |
Time |
DateFormat |
Real Number |
Time. |
Semi-major Axis |
DistanceUnit |
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 |
AngleUnit |
Real Number |
The angle between the orbit plane and the XY plane
of the coordinate system. |
RAAN |
LongitudeUnit |
Real Number |
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. The Calc Object allows a choice of coordinate
systems. The default is Earth Centered Inertial. |
Arg of Perigee |
AngleUnit |
Real Number |
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 |
AngleUnit |
Real Number |
The angle from the periapsis vector, measured in
the orbit plane in the direction of motion, to the position
vector. |
Mean Anomaly |
AngleUnit |
Real Number |
A measure of the time past periapsis passing,
expressed as an angle. |
Arg of Latitude |
AngleUnit |
Real Number |
The sum of the true anomaly and the argument of
periapsis.. |
Apogee Altitude |
DistanceUnit |
Real Number |
The difference between the radius of apoapsis and
the central body's equatorial radius. |
Apogee Radius |
DistanceUnit |
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 |
DistanceUnit |
Real Number |
The difference between the radius of periapsis and
the central body's equatorial radius. |
Perigee Radius |
DistanceUnit |
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 |
LongitudeUnit |
Real Number |
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 |
AngleUnit |
Real Number |
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 |
TimeUnit |
Real Number |
The elapsed time since passing the last ascending
node crossing based on assumed two-body motion.. |
Time Past
Perigee |
TimeUnit |
Real Number |
The elapsed time since passing the last periapsis
crossing based on assumed two-body motion.. |
Period |
TimeUnit |
Real Number |
The time to complete an entire cycle. |
Longitude of
Perigee |
LongitudeUnit |
Real Number |
The sum of the right ascension of the ascending
node and the argument of periapsis. |
Mean Longitude |
LongitudeUnit |
Real Number |
mean longitude is the sum:
right_ascension_of_the_ascending_node + argument_of_periapse +
mean_anomaly. A measure of the location within the orbit. |