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

Function Documentation

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

Converts a state vector from GCRF to ITRF (ECI to ECEF) at epoch t_tdb.

If InitFrameConversionFromSpice has fitted a SPICE-derived EOP model (see ComputeEopFromSpice) covering t_tdb, RotPolarMotion/ RotSideralMotion[Dot] transparently use the fitted EOP, so that this matches lupnt::spice::ConvertFrameSpice closely.

Used throughout the simulator wherever inertial states (propagated dynamics, SPICE ephemerides) must be expressed in the Earth-fixed frame — e.g. ground station visibility, ECEF-frame measurements, and ITRF-referenced outputs.

Note

Astrodynamics Convention & Modeling Reference, Version 1.1, Page 37

Parameters:

  • t_tdb – Epoch [s, TDB since J2000]

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

Returns:

Position+velocity in ITRF (ECEF) [m, m/s]