Function lupnt::GcrfToMoonCi(Real, const Vec6&)

Function Documentation

Vec6 lupnt::GcrfToMoonCi(Real t_tdb, const Vec6 &rv_gcrf)

Converts a state vector from GCRF (Earth-centered inertial) to MoonCi (Moon-centered inertial, axes aligned with ICRF/GCRF), by subtracting the Earth-to-Moon position/velocity at t_tdb.

Used by ConvertFrame as the entry point into the Moon-centered frame family (MoonCi/MoonPa/MoonMe/MoonOp) — e.g. when expressing a lunar orbiter’s or surface asset’s inertial state relative to the Moon instead of the Earth.

Note

Astrodynamics Convention & Modeling Reference, Version 1.1, Page 40

Parameters:

  • t_tdb – Epoch [s, TDB since J2000]

  • rv_gcrf – Position+velocity in GCRF (Earth-centered) [m, m/s]

Returns:

Position+velocity in MoonCi (Moon-centered inertial) [m, m/s]