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# -*- coding: utf-8 -*-
# Licensed under a 3-clause BSD style license - see LICENSE.rst
"""
This package defines magnitude zero points. By default, they are used to
define corresponding magnitudes, but not enabled as regular physical units.
To enable them, do::
>>> from astropy.units import magnitude_zero_points
>>> magnitude_zero_points.enable() # doctest: +SKIP
"""
from __future__ import (absolute_import, division, print_function,
unicode_literals)
import numpy as _numpy
from ..core import UnitBase, def_unit
# One cannot import L_bol0 directly, or the order of imports of units and
# constants starts to matter on python2. [#5121]
from ...constants import si as _si
from .. import si, astrophys
_ns = globals()
def_unit(['Bol', 'L_bol'], _si.L_bol0, namespace=_ns, prefixes=False,
doc="Luminosity corresponding to absolute bolometric magnitude zero")
def_unit(['bol', 'f_bol'], _si.L_bol0 / (4 * _numpy.pi * (10.*astrophys.pc)**2),
namespace=_ns, prefixes=False, doc="Irradiance corresponding to "
"appparent bolometric magnitude zero")
def_unit(['AB'], 10.**(-0.4*48.6) * 1.e-3 * si.W / si.m**2 / si.Hz,
namespace=_ns, prefixes=False,
doc="AB magnitude zero flux density.")
def_unit(['ST'], 10.**(-0.4*21.1) * 1.e-3 * si.W / si.m**2 / si.AA,
namespace=_ns, prefixes=False,
doc="ST magnitude zero flux density.")
###########################################################################
# CLEANUP
del UnitBase
del def_unit
del si
del 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())
def enable():
"""
Enable magnitude zero point units so they appear in results of
`~astropy.units.UnitBase.find_equivalent_units` and
`~astropy.units.UnitBase.compose`.
This may be used with the ``with`` statement to enable these
units only temporarily.
"""
# Local import to avoid cyclical import
from ..core import add_enabled_units
# Local import to avoid polluting namespace
import inspect
return add_enabled_units(inspect.getmodule(enable))
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