Skip to main content
`Ctrl`+`K`

# Source code for astropy.coordinates.builtin_frames.hcrs

    # Licensed under a 3-clause BSD style license - see LICENSE.rst

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

    from .baseradec import BaseRADecFrame, doc_components
    from .utils import DEFAULT_OBSTIME

    __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.
    """

    @format_doc(base_doc, components=doc_components, footer=doc_footer)
    class HCRS(BaseRADecFrame):
        """
        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:astropy-coordinates-seealso`
        section of the documentation.

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

        obstime = TimeAttribute(
            default=DEFAULT_OBSTIME, doc="The reference time (e.g., time of observation)"
        )

    # Transformations are defined in icrs_circ_transforms.py