heyoka.model.rot_teme_itrs

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heyoka.model.rot_teme_itrs#

heyoka.model.rot_teme_itrs(xyz: Iterable[expression], time_expr: expression = heyoka.time, eop_data: eop_data = eop_data()) → list[expression]#

Rotation from TEME to ITRS.

Added in version 7.5.0.

This function will rotate the input Cartesian coordinates xyz from the axes of the TEME (True Equator Mean Equinox) frame to the axes of the ITRS frame.

TEME is the reference frame adopted by the SGP analytical models, which are used to propagate orbital motion via two-line element sets produced by NORAD and NASA.

Different implementations of the TEME frame exist. For clarity, this implementation follows the conventions and relations to other frames that are set out in [VCHK06]. Specifically, the TEME frame is realised by an initial rotation from the ITRS to the Pseudo-Earth fixed (PEF) frame, which removes the effects of polar motion, followed by a rotation around the \(z\) axis to account for the Greenwich mean sidereal time (GMST) (see gmst82()).

The rotation depends on the input time time_expr (which is expected to represent the number of Julian centuries elapsed since the epoch of J2000 in the terrestrial time scale (TT)) and it also requires in input an Earth orientation parameters dataset eop_data. Please see the documentation of eop_data for more information.

Parameters:

  • xyz – the input Cartesian coordinates.

  • time_expr – the input time expression.

  • eop_data – the EOP data to be used for the computation.

Returns:

the rotated Cartesian coordinates.

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