Geocentric¶

Geocentric (spherical Earth) coordinate transformations.

Converts between geocentric coordinates [longitude, latitude, altitude] and Earth-Centered Earth-Fixed (ECEF) Cartesian coordinates [x, y, z].

The geocentric model treats the Earth as a perfect sphere with radius equal to the WGS84 semi-major axis. For an ellipsoidal model, use the geodetic functions in :mod:astrojax.coordinates.geodetic.

All inputs and outputs use SI base units (metres, radians).

References

O. Montenbruck and E. Gill, Satellite Orbits: Models, Methods and Applications, Springer, 2012, Sec. 5.3.

`position_ecef_to_geocentric(x_ecef, use_degrees=False)` ¶

Convert ECEF Cartesian coordinates to geocentric position.

Parameters:

Name	Type	Description	Default
`x_ecef`	`ArrayLike`	ECEF position `[x, y, z]` in m.	required
`use_degrees`	`bool`	If `True`, return longitude and latitude in degrees.	`False`

Returns:

Type	Description
`Array`	Geocentric coordinates `[lon, lat, alt]`. Longitude and latitude in rad (or deg), altitude in m.

Examples:

import jax.numpy as jnp
from astrojax.constants import WGS84_a
from astrojax.coordinates import position_ecef_to_geocentric
x_ecef = jnp.array([WGS84_a, 0.0, 0.0])
geoc = position_ecef_to_geocentric(x_ecef)
float(geoc[2])  # altitude ≈ 0

`position_geocentric_to_ecef(x_geoc, use_degrees=False)` ¶

Convert geocentric position to ECEF Cartesian coordinates.