Description of orbital elements
In addition, a "pv" type has been defined. It corresponds to "position and velocity" (in a (6xN) matrix).
Apart from position and velocity that can always be used, the suitable orbital element types are:
Elliptical orbits: "kep", "cir", "cireq" or "equin"
(preferably: "kep": for not near-circular and not near-equatorial orbits, "cir" for near-circular and not near-equatorial),
Hyperbolic orbits: "kep" only.
(Note that the semi major axis of a hyperbolic orbit is positive by convention.)
Parabolic orbits: none!
When converting to "kep" or "cir" types:
The thresholds used to determine if an orbit is near-circular, near-equatorial or near-parabolic are defined as constants - see "Data files" in CelestLab menu for values.