# -*- coding: utf-8 -*-
# Licensed under a 3-clause BSD style license - see LICENSE.rst
from __future__ import (absolute_import, unicode_literals, division,
print_function)
from ... import units as u
from .. import representation as r
from ..baseframe import BaseCoordinateFrame, RepresentationMapping
from .galactic import Galactic
[docs]class Supergalactic(BaseCoordinateFrame):
"""
Supergalactic Coordinates
(see Lahav et al. 2000, <http://adsabs.harvard.edu/abs/2000MNRAS.312..166L>,
and references therein).
Parameters
----------
representation : `BaseRepresentation` or None
A representation object or None to have no data (or use the other keywords)
sgl : `Angle`, optional, must be keyword
The supergalactic longitude for this object (``sgb`` must also be given and
``representation`` must be None).
sgb : `Angle`, optional, must be keyword
The supergalactic latitude for this object (``sgl`` must also be given and
``representation`` must be None).
distance : `~astropy.units.Quantity`, optional, must be keyword
The Distance for this object along the line-of-sight.
pm_sgl_cossgb : :class:`~astropy.units.Quantity`, optional, must be keyword
The proper motion in Right Ascension for this object (``pm_sgb`` must
also be given).
pm_sgb : :class:`~astropy.units.Quantity`, optional, must be keyword
The proper motion in Declination for this object (``pm_sgl_cossgb`` must
also be given).
radial_velocity : :class:`~astropy.units.Quantity`, optional, must be keyword
The radial velocity of this object.
copy : bool, optional
If `True` (default), make copies of the input coordinate arrays.
Can only be passed in as a keyword argument.
differential_cls : `BaseDifferential`, dict, optional
A differential class or dictionary of differential classes (currently
only a velocity differential with key 's' is supported). This sets
the expected input differential class, thereby changing the expected
keyword arguments of the data passed in. For example, passing
``differential_cls=CartesianDifferential`` will make the classes
expect velocity data with the argument names ``v_x, v_y, v_z``.
"""
frame_specific_representation_info = {
r.SphericalRepresentation: [
RepresentationMapping('lon', 'sgl'),
RepresentationMapping('lat', 'sgb')
],
r.CartesianRepresentation: [
RepresentationMapping('x', 'sgx'),
RepresentationMapping('y', 'sgy'),
RepresentationMapping('z', 'sgz')
],
r.SphericalCosLatDifferential: [
RepresentationMapping('d_lon_coslat', 'pm_sgl_cossgb', u.mas/u.yr),
RepresentationMapping('d_lat', 'pm_sgb', u.mas/u.yr),
RepresentationMapping('d_distance', 'radial_velocity', u.km/u.s),
],
r.SphericalDifferential: [
RepresentationMapping('d_lon', 'pm_sgl', u.mas/u.yr),
RepresentationMapping('d_lat', 'pm_sgb', u.mas/u.yr),
RepresentationMapping('d_distance', 'radial_velocity', u.km/u.s),
],
r.CartesianDifferential: [
RepresentationMapping('d_x', 'v_x', u.km/u.s),
RepresentationMapping('d_y', 'v_y', u.km/u.s),
RepresentationMapping('d_z', 'v_z', u.km/u.s)
],
}
frame_specific_representation_info[r.UnitSphericalRepresentation] = \
frame_specific_representation_info[r.SphericalRepresentation]
frame_specific_representation_info[r.UnitSphericalCosLatDifferential] = \
frame_specific_representation_info[r.SphericalCosLatDifferential]
frame_specific_representation_info[r.UnitSphericalDifferential] = \
frame_specific_representation_info[r.SphericalDifferential]
default_representation = r.SphericalRepresentation
default_differential = r.SphericalCosLatDifferential
# North supergalactic pole in Galactic coordinates.
# Needed for transformations to/from Galactic coordinates.
_nsgp_gal = Galactic(l=47.37*u.degree, b=+6.32*u.degree)