ITRF

spacekernel.frames.ITRF = <spacekernel.frames.frames._ITRF object>

International Terrestrial Reference Frame (ITRF).

The ITRF is a standard, Earth-centered, Earth-fixed (ECEF) reference frame used for geodetic, geophysical, and orbital computations. This class provides high-precision transformations from ITRF to both GCRF and TEME frames, compliant with IAU and IERS conventions.

See also

GCRF

Geocentric Celestial Reference Frame

TEME

True Equator Mean Equinox Frame

Frame

Base class for reference frames

Notes

• Implements direct transformations:

  • ITRF → GCRF using IAU 2000A CIO-based conventions

  • ITRF → TEME using GMST82 rotation

• All transformations use Earth Orientation Parameters (EOP) and proper handling of polar motion, precession, nutation, and sidereal time as specified in:

  • SOFA Cookbook (sofa_pn_c.pdf)

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

Summary

_ITRF.to_GCRF(self, time, r_ITRF, v_ITRF)	Transform position and velocity from ITRF to GCRF.
_ITRF.to_TEME(self, time, r_ITRF, v_ITRF)	Transform position and velocity from ITRF to TEME.

Methods

_ITRF.to_GCRF(self, time: DatetimeLike, r_ITRF: ndarray[double], v_ITRF: ndarray[double]) → tuple[ndarray, 2]

Transform position and velocity from ITRF to GCRF.

Parameters:

timeDatetimeLike

Time(s) for which the transformation is computed.

r_ITRFndarray of shape (N, 3)

Position vectors in the ITRF frame.

v_ITRFndarray of shape (N, 3)

Velocity vectors in the ITRF frame.

Returns:

r_GCRFndarray of shape (N, 3)

Transformed position vectors in the GCRF frame.

v_GCRFndarray of shape (N, 3)

Transformed velocity vectors in the GCRF frame.

Notes

This method calls the low-level Cython implementation c_to_GCRF.

_ITRF.to_TEME(self, time: DatetimeLike, r_ITRF: ndarray[double], v_ITRF: ndarray[double]) → tuple[ndarray, 2]

Transform position and velocity from ITRF to TEME.

Parameters:

timeDatetimeLike

Time(s) for which the transformation is computed.

r_ITRFndarray of shape (N, 3)

Position vectors in the ITRF frame.

v_ITRFndarray of shape (N, 3)

Velocity vectors in the ITRF frame.

Returns:

r_TEMEndarray of shape (N, 3)

Transformed position vectors in the TEME frame.

v_TEMEndarray of shape (N, 3)

Transformed velocity vectors in the TEME frame.

Notes

This method calls the low-level Cython implementation c_to_TEME.