heyoka.model.gmst82

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heyoka.model.gmst82#

heyoka.model.gmst82(time_expr: expression = heyoka.time, eop_data: eop_data = eop_data()) → expression#

Greenwich mean sidereal time (IAU 1982 model).

Added in version 7.5.0.

This function will return an expression representing the Greenwich mean sidereal time (GMST) according to the IAU 1982 model as a function of the input time expression time_expr. time_expr is expected to represent the number of Julian centuries elapsed since the epoch of J2000 in the terrestrial time scale (TT). eop_data is the Earth orientation parameters dataset to be used for the computation.

The GMST is modelled as a piecewise linear function of time, where the switch points are given by the dates in eop_data. Evaluation of the GMST outside the dates range of eop_data will produce a value of NaN.

The GMST is returned in radians, reduced to the \(\left[0, 2\pi\right]\) range.

Parameters:

  • time_expr – the input time expression.

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

Returns:

an expression for the GMST as a function of time.

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