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# Source code for astropy.units.photometric

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

    """
    This module defines magnitude zero points and related photometric quantities.

    The corresponding magnitudes are given in the description of each unit
    (the actual definitions are in `~astropy.units.function.logarithmic`).
    """

    import numpy as _numpy

    from astropy.constants import si as _si

    from . import astrophys, cgs, si
    from .core import Unit, UnitBase, def_unit

    _ns = globals()

    def_unit(
        ["Bol", "L_bol"],
        _si.L_bol0,
        namespace=_ns,
        prefixes=False,
        doc=(
            "Luminosity corresponding to absolute bolometric magnitude zero "
            "(magnitude ``M_bol``)."
        ),
    )
    def_unit(
        ["bol", "f_bol"],
        _si.L_bol0 / (4 * _numpy.pi * (10.0 * astrophys.pc) ** 2),
        namespace=_ns,
        prefixes=False,
        doc=(
            "Irradiance corresponding to appparent bolometric magnitude zero "
            "(magnitude ``m_bol``)."
        ),
    )
    def_unit(
        ["AB", "ABflux"],
        10.0 ** (48.6 / -2.5) * cgs.erg * cgs.cm**-2 / si.s / si.Hz,
        namespace=_ns,
        prefixes=False,
        doc="AB magnitude zero flux density (magnitude ``ABmag``).",
    )
    def_unit(
        ["ST", "STflux"],
        10.0 ** (21.1 / -2.5) * cgs.erg * cgs.cm**-2 / si.s / si.AA,
        namespace=_ns,
        prefixes=False,
        doc="ST magnitude zero flux density (magnitude ``STmag``).",
    )
    def_unit(
        ["mgy", "maggy"],
        namespace=_ns,
        prefixes=[(["n"], ["nano"], 1e-9)],
        doc=(
            "Maggies - a linear flux unit that is the flux for a mag=0 object."
            "To tie this onto a specific calibrated unit system, the "
            "zero_point_flux equivalency should be used."
        ),
    )

    def zero_point_flux(flux0):
        """
        An equivalency for converting linear flux units ("maggys") defined relative
        to a standard source into a standardized system.

        Parameters
        ----------
        flux0 : `~astropy.units.Quantity`
            The flux of a magnitude-0 object in the "maggy" system.
        """
        flux_unit0 = Unit(flux0)
        return [(maggy, flux_unit0)]

    ###########################################################################
    # CLEANUP

    del UnitBase
    del def_unit
    del cgs, si, astrophys

    ###########################################################################
    # DOCSTRING

    # This generates a docstring for this module that describes all of the
    # standard units defined here.
    from .utils import generate_unit_summary as _generate_unit_summary

    if __doc__ is not None:
        __doc__ += _generate_unit_summary(globals())