class astropy.coordinates.solar_system_ephemeris[source] [edit on github]

Bases: astropy.utils.state.ScienceState

Default ephemerides for calculating positions of Solar-System bodies.

This can be one of the following:

- 'builtin': polynomial approximations to the orbital elements.
- 'de430' or 'de432s': short-cuts for recent JPL dynamical models.
- 'jpl': Alias for the default JPL ephemeris (currently, 'de430').
- URL: (str) The url to a SPK ephemeris in SPICE binary (.bsp) format.
- `None`: Ensure an Exception is raised without an explicit ephemeris.

The default is ‘builtin’, which uses the epv00 and plan94 routines from the erfa implementation of the Standards Of Fundamental Astronomy library.


Any file required will be downloaded (and cached) when the state is set. The default Satellite Planet Kernel (SPK) file from NASA JPL (de430) is ~120MB, and covers years ~1550-2650 CE [1]. The smaller de432s file is ~10MB, and covers years 1950-2050 [2]. Older versions of the JPL ephemerides (such as the widely used de200) can be used via their URL [3].


Attributes Summary


Methods Summary

validate(value) Validate the value and convert it to its native type, if necessary.

Attributes Documentation


Methods Documentation

classmethod get_kernel(value)[source] [edit on github]
classmethod validate(value)[source] [edit on github]

Validate the value and convert it to its native type, if necessary.