GCRF

spacekernel.frames.GCRF = <spacekernel.frames.frames._GCRF object>

Geocentric Celestial Reference Frame (GCRF).

The GCRF is a quasi-inertial reference frame centered at the Earth’s center of mass, aligned with the International Celestial Reference Frame (ICRF) axes. This class provides methods to transform state vectors from GCRF to the International Terrestrial Reference Frame (ITRF) using high-precision IAU 2000A CIO-based algorithms, compliant with IERS conventions.

See also

ITRF

International Terrestrial Reference Frame

Frame

Base class for reference frames

Notes

• The transformation follows IAU 2000A and IERS 2003 conventions, incorporating precession, nutation, Earth rotation, polar motion, and Earth orientation parameters (EOP).

• Main references:

  • SOFA Cookbook, Section 5 (sofa_pn_c.pdf)

  • Vallado, D.A., “Fundamentals of Astrodynamics and Applications”, 4th Ed., Algorithm 23.

• This class is typically used internally as part of a reference frame transformation graph.

Summary

_GCRF.to_ITRF(self, time, r_GCRF, v_GCRF)

Transform position and velocity from GCRF to ITRF.

Methods

_GCRF.to_ITRF(self, time: DatetimeLike, r_GCRF: ndarray[double], v_GCRF: ndarray[double]) → tuple[ndarray, 2]

Transform position and velocity from GCRF to ITRF.

Parameters:

timeDatetimeLike

Time(s) for which the transformation is computed.

r_GCRFndarray of shape (N, 3)

Position vectors in the GCRF frame.

v_GCRFndarray of shape (N, 3)

Velocity vectors in the GCRF frame.

Returns:

r_ITRFndarray of shape (N, 3)

Transformed position vectors in the ITRF frame.

v_ITRFndarray of shape (N, 3)

Transformed velocity vectors in the ITRF frame.

Notes

This method calls the low-level Cython implementation c_to_ITRF.