Initial Conditions

An orbit may be defined given a state vector and reference frame. Within eom, state vectors are composed of six parameters and an associated epoch time. Using this definition, the state vector alone typically will not be sufficient to accurately propagate an orbit. For SP methods, additional information about how the state vector was fit will be required (Propagator Configuration).

State Vector Type

The state vector type indicates the coordinate system used to specify state vector components.

CART

Cartesian coordinates composed of three position and three velocity elements.

KEP_T

Keplerian elements composed of semimajor axis, eccentricity, inclination, right ascension of the ascending node, argument of perigee, and true anomaly. Only earth centered inertial reference frames may be used with this option.
  AngleUnits  Degrees;
  # Default units of DU for semimajor axis
  #               a      e     i      o      w     v
  KEP_T  GCRF  4.1632  0.741  63.4  345.0  270.0  0.0;

Reference Frame

Not all settings taking a reference frame type accept all available reference frames.

GCRF

Cartesian geocentric celestial reference frame

ITRF

Cartesian international terrestrial reference frame

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