Skip to content

Equinoctial Elements

py_outfit.orbit_type.equinoctial.EquinoctialElements 

EquinoctialElements(
    reference_epoch: float,
    semi_major_axis: float,
    eccentricity_sin_lon: float,
    eccentricity_cos_lon: float,
    tan_half_incl_sin_node: float,
    tan_half_incl_cos_node: float,
    mean_longitude: float,
)

Equinoctial orbital elements.

Definitions
  • h = e * sin(ϖ) with ϖ = Ω + ω
  • k = e * cos(ϖ)
  • p = tan(i/2) * sin(Ω)
  • q = tan(i/2) * cos(Ω)
  • λ (here mean_longitude) = mean longitude (rad), i.e. Ω + ω + M in the usual convention
Units
  • reference_epoch: MJD (TDB)
  • semi_major_axis: AU
  • h, k, p, q: dimensionless
  • mean_longitude: radians
See also
  • to_keplerian — Convert to Keplerian elements.
RETURNS DESCRIPTION
EquinoctialElements

A new equinoctial element set.

reference_epoch property 

reference_epoch: float

Reference epoch of the element set (MJD, TDB).

semi_major_axis property 

semi_major_axis: float

Semi-major axis a (AU).

eccentricity_sin_lon property 

eccentricity_sin_lon: float

h = e * sin(ϖ), dimensionless.

eccentricity_cos_lon property 

eccentricity_cos_lon: float

k = e * cos(ϖ), dimensionless.

tan_half_incl_sin_node property 

tan_half_incl_sin_node: float

p = tan(i/2) * sin(Ω), dimensionless.

tan_half_incl_cos_node property 

tan_half_incl_cos_node: float

q = tan(i/2) * cos(Ω), dimensionless.

mean_longitude property 

mean_longitude: float

Mean longitude λ (radians).

to_keplerian 

to_keplerian() -> KeplerianElements

Convert equinoctial → Keplerian elements.

RETURNS DESCRIPTION
KeplerianElements

The equivalent Keplerian elements.