Convert a GCRS position to ITRS (Earth-fixed / ECEF).

Accepts a map with a :position tuple (km) and a datetime. Pass skyfield_compat: true for 0 ULP Skyfield parity.

Returns {x, y, z} in km.

Convert a TEME state vector to GCRS.

Accepts a map with :position and :velocity tuples (km and km/s), and a datetime (either DateTime or {{y,m,d},{h,m,s}} tuple).

Options

• :skyfield_compat - when true, uses Skyfield's exact computation path (AU scaling, Kahan triple product, FMA multiply) for 0 ULP parity. Default false uses direct km arithmetic which is more numerically precise.

Returns a map with GCRS :position and :velocity.

Convert an ITRS/ECEF position to WGS84 geodetic coordinates.

Accepts a position tuple {x, y, z} in km.

Returns %{latitude: degrees, longitude: degrees, altitude_km: km}.

Compute topocentric azimuth, elevation, and range from a ground station to a satellite given in GCRS.

Parameters

• gcrs_state - map with :position tuple (km) in GCRS
• datetime - observation time
• station - %{latitude: deg, longitude: deg, altitude_m: meters}

Returns %{azimuth: degrees, elevation: degrees, range_km: km}.