Struct

`space::irbem::HelioGeometry`

cheatah-space v0.1.0-alpha — Biome Standard 0.6.5-alpha

The Sun–Earth geometry at one epoch — everything the six heliospheric transforms need, evaluated once so that no transform pays for trigonometry.

A plain aggregate of doubles and two matrices: trivially copyable, nothing allocated, and cheap enough to hold one per ephemeris sample or to rebuild per time step, whichever the caller prefers.

Constants & variables

var double earth_longitude_deg #

The Earth's heliocentric ecliptic longitude λ_geo of date, degrees in [0, 360) (F&H eqn.

36). This is the angle that carries HAE into HEE.

var double apparent_earth_longitude_deg #

λ_geo corrected for light aberration, degrees in [0, 360) — the longitude of the apparent sub-Earth point on the solar disc, which is what defines the central meridian (F&H §3.2.1).

var double sun_earth_distance_au #

The Sun–Earth distance r₀ in astronomical units (F&H eqn. 36).

var double sun_earth_distance_re #

The same distance in Earth radii — the translation between the geocentric and heliocentric origins, in the unit this module's positions use.

var double solar_node_deg #

The ascending node Ω of the solar equator on the ecliptic of date, degrees in [0, 360) (F&H eqn.

14).

var double solar_central_meridian_deg #

The central-meridian angle θ: the heliographic longitude of the sub-Earth point measured from Ω, degrees in [0, 360) (F&H eqn.

17).

var fixarray::mat3d hae_to_hee #

<λ_geo, Z> — the rotation carrying HAE components into HEE (F&H §3.2.2).

var fixarray::mat3d hae_to_heeq #

<θ, Z>·<i, X>·<Ω, Z> — the rotation carrying HAE components into HEEQ (F&H §3.2.2).