heyoka.model.egm2008_acc

Contents

heyoka.model.egm2008_acc#

heyoka.model.egm2008_acc(xyz: Iterable[expression], n: int, m: int, mu: expression = 398600441500000, a: expression = 6378136.3) → list[expression]#

Gravitational acceleration (EGM2008).

Added in version 7.3.0.

This function will return the value of the Earth’s gravitational acceleration at the input Cartesian position xyz according to the EGM2008 model. xyz is expected to represent the position vector with respect to the Earth-centred Earth-fixed WGS84 frame (which itself can be considered coincident with the ITRF).

n and m are, respectively, the maximum harmonic degree and order to be considered in the computation. Higher degrees and orders will produce more accurate values, at the cost of increased computational complexity.

mu and a are, respectively, the gravitational parameter and reference Earth radius to be used in the computation. Both are expected to be provided in units consistent with each other and with xyz. The default values (in SI units) are those specified in the documentation of the EGM2008 model.

Note

Currently this function implements a version of EGM2008 in which the maximum degree and order are capped below those of the full model.

Parameters:

  • xyz – the position at which the acceleration will be evaluated.

  • n – the maximum harmonic degree to be used in the computation.

  • m – the maximum harmonic order to be used in the computation.

  • mu – the Earth’s gravitational parameter.

  • a – the reference Earth radius.

Returns:

an expression for the Cartesian acceleration vector due to the geopotential at the position xyz.

Raises:

ValueError – it m > n or if n is larger than an implementation-defined limit.

Contents