galactocentric_frame_defaults

class astropy.coordinates.galactocentric_frame_defaults[source]

Bases: astropy.utils.state.ScienceState

This class controls the global setting of default values for the frame attributes in the Galactocentric frame, which may be updated in future versions of astropy. Note that when using Galactocentric, changing values here will not affect any attributes that are set explicitly by passing values in to the Galactocentric initializer. Modifying these defaults will only affect the frame attribute values when using the frame as, e.g., Galactocentric or Galactocentric() with no explicit arguments.

This class controls the parameter settings by specifying a string name, which can be one of:

  • ‘pre-v4.0’: The current default value, which sets the default frame attribute values to their original (pre-astropy-v4.0) values.
  • ‘v4.0’: The attribute values as updated in Astropy version 4.0.
  • ‘latest’: An alias of the most recent parameter set (currently: ‘v4.0’)

See Controlling the Default Frame Parameters for more information.

Examples

The default Galactocentric frame parameters can be modified globally:

>>> from astropy.coordinates import galactocentric_frame_defaults
>>> _ = galactocentric_frame_defaults.set('v4.0')
>>> Galactocentric() 
<Galactocentric Frame (galcen_coord=<ICRS Coordinate: (ra, dec) in deg
    (266.4051, -28.936175)>, galcen_distance=8.122 kpc, galcen_v_sun=(12.9, 245.6, 7.78) km / s, z_sun=20.8 pc, roll=0.0 deg)>
>>> _ = galactocentric_frame_defaults.set('pre-v4.0')
>>> Galactocentric() 
<Galactocentric Frame (galcen_coord=<ICRS Coordinate: (ra, dec) in deg
    (266.4051, -28.936175)>, galcen_distance=8.3 kpc, galcen_v_sun=(11.1, 232.24, 7.25) km / s, z_sun=27.0 pc, roll=0.0 deg)>

The default parameters can also be updated by using this class as a context manager:

>>> with galactocentric_frame_defaults.set('pre-v4.0'):
...     print(Galactocentric()) 
<Galactocentric Frame (galcen_coord=<ICRS Coordinate: (ra, dec) in deg
    (266.4051, -28.936175)>, galcen_distance=8.3 kpc, galcen_v_sun=(11.1, 232.24, 7.25) km / s, z_sun=27.0 pc, roll=0.0 deg)>

Again, changing the default parameter values will not affect frame attributes that are explicitly specified:

>>> import astropy.units as u
>>> with galactocentric_frame_defaults.set('pre-v4.0'):
...     print(Galactocentric(galcen_distance=8.0*u.kpc)) 
<Galactocentric Frame (galcen_coord=<ICRS Coordinate: (ra, dec) in deg
    (266.4051, -28.936175)>, galcen_distance=8.0 kpc, galcen_v_sun=(11.1, 232.24, 7.25) km / s, z_sun=27.0 pc, roll=0.0 deg)>

Methods Summary

get_solar_params_from_string(arg) Return Galactocentric solar parameters given string names for the parameter sets.
validate(value) Validate the value and convert it to its native type, if necessary.

Methods Documentation

static get_solar_params_from_string(arg)[source]

Return Galactocentric solar parameters given string names for the parameter sets.

classmethod validate(value)[source]

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