# Licensed under a 3-clause BSD style license - see LICENSE.rst
from astropy import units as u
from astropy.coordinates import representation as r
from astropy.coordinates.attributes import QuantityAttribute, TimeAttribute
from astropy.coordinates.baseframe import BaseCoordinateFrame, base_doc
from astropy.utils.decorators import format_doc
from .utils import DEFAULT_OBSTIME, EQUINOX_J2000
__all__ = [
"GeocentricMeanEcliptic",
"BarycentricMeanEcliptic",
"HeliocentricMeanEcliptic",
"BaseEclipticFrame",
"GeocentricTrueEcliptic",
"BarycentricTrueEcliptic",
"HeliocentricTrueEcliptic",
"HeliocentricEclipticIAU76",
"CustomBarycentricEcliptic",
]
doc_components_ecl = """
lon : `~astropy.coordinates.Angle`, optional, keyword-only
The ecliptic longitude for this object (``lat`` must also be given and
``representation`` must be None).
lat : `~astropy.coordinates.Angle`, optional, keyword-only
The ecliptic latitude for this object (``lon`` must also be given and
``representation`` must be None).
distance : `~astropy.units.Quantity` ['length'], optional, keyword-only
The distance for this object from the {0}.
(``representation`` must be None).
pm_lon_coslat : `~astropy.units.Quantity` ['angualar speed'], optional, keyword-only
The proper motion in the ecliptic longitude (including the ``cos(lat)``
factor) for this object (``pm_lat`` must also be given).
pm_lat : `~astropy.units.Quantity` ['angular speed'], optional, keyword-only
The proper motion in the ecliptic latitude for this object
(``pm_lon_coslat`` must also be given).
radial_velocity : `~astropy.units.Quantity` ['speed'], optional, keyword-only
The radial velocity of this object.
"""
[docs]
@format_doc(
base_doc, components=doc_components_ecl.format("specified location"), footer=""
)
class BaseEclipticFrame(BaseCoordinateFrame):
"""
A base class for frames that have names and conventions like that of
ecliptic frames.
.. warning::
In the current version of astropy, the ecliptic frames do not yet have
stringent accuracy tests. We recommend you test to "known-good" cases
to ensure this frames are what you are looking for. (and then ideally
you would contribute these tests to Astropy!)
"""
default_representation = r.SphericalRepresentation
default_differential = r.SphericalCosLatDifferential
doc_footer_geo = """
Other parameters
----------------
equinox : `~astropy.time.Time`, optional
The date to assume for this frame. Determines the location of the
x-axis and the location of the Earth (necessary for transformation to
non-geocentric systems). Defaults to the 'J2000' equinox.
obstime : `~astropy.time.Time`, optional
The time at which the observation is taken. Used for determining the
position of the Earth. Defaults to J2000.
"""
[docs]
@format_doc(
base_doc, components=doc_components_ecl.format("geocenter"), footer=doc_footer_geo
)
class GeocentricMeanEcliptic(BaseEclipticFrame):
"""
Geocentric mean ecliptic coordinates. These origin of the coordinates are the
geocenter (Earth), with the x axis pointing to the *mean* (not true) equinox
at the time specified by the ``equinox`` attribute, and the xy-plane in the
plane of the ecliptic for that date.
Be aware that the definition of "geocentric" here means that this frame
*includes* light deflection from the sun, aberration, etc when transforming
to/from e.g. ICRS.
The frame attributes are listed under **Other Parameters**.
"""
equinox = TimeAttribute(default=EQUINOX_J2000, doc="The equinox time")
obstime = TimeAttribute(
default=DEFAULT_OBSTIME, doc="The reference time (e.g., time of observation)"
)
[docs]
@format_doc(
base_doc, components=doc_components_ecl.format("geocenter"), footer=doc_footer_geo
)
class GeocentricTrueEcliptic(BaseEclipticFrame):
"""
Geocentric true ecliptic coordinates. These origin of the coordinates are the
geocenter (Earth), with the x axis pointing to the *true* (not mean) equinox
at the time specified by the ``equinox`` attribute, and the xy-plane in the
plane of the ecliptic for that date.
Be aware that the definition of "geocentric" here means that this frame
*includes* light deflection from the sun, aberration, etc when transforming
to/from e.g. ICRS.
The frame attributes are listed under **Other Parameters**.
"""
equinox = TimeAttribute(default=EQUINOX_J2000, doc="The equinox time")
obstime = TimeAttribute(
default=DEFAULT_OBSTIME, doc="The reference time (e.g., time of observation)"
)
doc_footer_bary = """
Other parameters
----------------
equinox : `~astropy.time.Time`, optional
The date to assume for this frame. Determines the location of the
x-axis and the location of the Earth and Sun.
Defaults to the 'J2000' equinox.
"""
[docs]
@format_doc(
base_doc, components=doc_components_ecl.format("barycenter"), footer=doc_footer_bary
)
class BarycentricMeanEcliptic(BaseEclipticFrame):
"""
Barycentric mean ecliptic coordinates. These origin of the coordinates are the
barycenter of the solar system, with the x axis pointing in the direction of
the *mean* (not true) equinox as at the time specified by the ``equinox``
attribute (as seen from Earth), and the xy-plane in the plane of the
ecliptic for that date.
The frame attributes are listed under **Other Parameters**.
"""
equinox = TimeAttribute(default=EQUINOX_J2000, doc="The equinox time")
[docs]
@format_doc(
base_doc, components=doc_components_ecl.format("barycenter"), footer=doc_footer_bary
)
class BarycentricTrueEcliptic(BaseEclipticFrame):
"""
Barycentric true ecliptic coordinates. These origin of the coordinates are the
barycenter of the solar system, with the x axis pointing in the direction of
the *true* (not mean) equinox as at the time specified by the ``equinox``
attribute (as seen from Earth), and the xy-plane in the plane of the
ecliptic for that date.
The frame attributes are listed under **Other Parameters**.
"""
equinox = TimeAttribute(default=EQUINOX_J2000, doc="The equinox time")
doc_footer_helio = """
Other parameters
----------------
equinox : `~astropy.time.Time`, optional
The date to assume for this frame. Determines the location of the
x-axis and the location of the Earth and Sun.
Defaults to the 'J2000' equinox.
obstime : `~astropy.time.Time`, optional
The time at which the observation is taken. Used for determining the
position of the Sun. Defaults to J2000.
"""
[docs]
@format_doc(
base_doc,
components=doc_components_ecl.format("sun's center"),
footer=doc_footer_helio,
)
class HeliocentricMeanEcliptic(BaseEclipticFrame):
"""
Heliocentric mean ecliptic coordinates. These origin of the coordinates are the
center of the sun, with the x axis pointing in the direction of
the *mean* (not true) equinox as at the time specified by the ``equinox``
attribute (as seen from Earth), and the xy-plane in the plane of the
ecliptic for that date.
The frame attributes are listed under **Other Parameters**.
{params}
"""
equinox = TimeAttribute(default=EQUINOX_J2000, doc="The equinox time")
obstime = TimeAttribute(
default=DEFAULT_OBSTIME, doc="The reference time (e.g., time of observation)"
)
[docs]
@format_doc(
base_doc,
components=doc_components_ecl.format("sun's center"),
footer=doc_footer_helio,
)
class HeliocentricTrueEcliptic(BaseEclipticFrame):
"""
Heliocentric true ecliptic coordinates. These origin of the coordinates are the
center of the sun, with the x axis pointing in the direction of
the *true* (not mean) equinox as at the time specified by the ``equinox``
attribute (as seen from Earth), and the xy-plane in the plane of the
ecliptic for that date.
The frame attributes are listed under **Other Parameters**.
{params}
"""
equinox = TimeAttribute(default=EQUINOX_J2000, doc="The equinox time")
obstime = TimeAttribute(
default=DEFAULT_OBSTIME, doc="The reference time (e.g., time of observation)"
)
[docs]
@format_doc(base_doc, components=doc_components_ecl.format("sun's center"), footer="")
class HeliocentricEclipticIAU76(BaseEclipticFrame):
"""
Heliocentric mean (IAU 1976) ecliptic coordinates. These origin of the coordinates are the
center of the sun, with the x axis pointing in the direction of
the *mean* (not true) equinox of J2000, and the xy-plane in the plane of the
ecliptic of J2000 (according to the IAU 1976/1980 obliquity model).
It has, therefore, a fixed equinox and an older obliquity value
than the rest of the frames.
The frame attributes are listed under **Other Parameters**.
{params}
"""
obstime = TimeAttribute(
default=DEFAULT_OBSTIME, doc="The reference time (e.g., time of observation)"
)
[docs]
@format_doc(base_doc, components=doc_components_ecl.format("barycenter"), footer="")
class CustomBarycentricEcliptic(BaseEclipticFrame):
"""
Barycentric ecliptic coordinates with custom obliquity.
These origin of the coordinates are the
barycenter of the solar system, with the x axis pointing in the direction of
the *mean* (not true) equinox of J2000, and the xy-plane in the plane of the
ecliptic tilted a custom obliquity angle.
The frame attributes are listed under **Other Parameters**.
"""
obliquity = QuantityAttribute(
default=84381.448 * u.arcsec, unit=u.arcsec, doc="The obliquity of the ecliptic"
)
