# Source code for astropy.coordinates.builtin_frames.hcrs

# -*- coding: utf-8 -*-

from astropy.utils.decorators import format_doc
from astropy.coordinates.attributes import TimeAttribute
from .utils import DEFAULT_OBSTIME
from astropy.coordinates.baseframe import base_doc

__all__ = ['HCRS']

doc_footer = """
Other parameters
----------------
obstime : ~astropy.time.Time
The time at which the observation is taken.  Used for determining the
position of the Sun.
"""

[docs]@format_doc(base_doc, components=doc_components, footer=doc_footer)
"""
A coordinate or frame in a Heliocentric system, with axes aligned to ICRS.

The ICRS has an origin at the Barycenter and axes which are fixed with
respect to space.

This coordinate system is distinct from ICRS mainly in that it is relative
to the Sun's center-of-mass rather than the solar system Barycenter.
In principle, therefore, this frame should include the effects of
aberration (unlike ICRS), but this is not done, since they are very small,
of the order of 8 milli-arcseconds.

For more background on the ICRS and related coordinate transformations, see
the references provided in the :ref:astropy-coordinates-seealso section of
the documentation.

The frame attributes are listed under **Other Parameters**.
"""

obstime = TimeAttribute(default=DEFAULT_OBSTIME)

# Transformations are defined in icrs_circ_transforms.py