def redden(flux,
wave=None,
photbands=None,
ebv=0.,
rtype='flux',
law='cardelli1989',
**kwargs):
"""
Redden flux or magnitudes
The reddening parameters C{ebv} means E(B-V).
If it is negative, we B{deredden}.
If you give the keyword C{wave}, it is assumed that you want to (de)redden
a B{model}, i.e. a spectral energy distribution.
If you give the keyword C{photbands}, it is assumed that you want to (de)redden
B{photometry}, i.e. integrated fluxes.
@param flux: fluxes to (de)redden (magnitudes if C{rtype='mag'})
@type flux: ndarray (floats)
@param wave: wavelengths matching the fluxes (or give C{photbands})
@type wave: ndarray (floats)
@param photbands: photometry bands matching the fluxes (or give C{wave})
@type photbands: ndarray of str
@param ebv: reddening parameter E(B-V)
@type ebv: float
@param rtype: type of dereddening (magnituds or fluxes)
@type rtype: str ('flux' or 'mag')
@return: (de)reddened flux/magnitude
@rtype: ndarray (floats)
"""
if photbands is not None:
wave = filters.get_info(photbands)['eff_wave']
old_settings = np.seterr(all='ignore')
wave, reddeningMagnitude = get_law(law, wave=wave, **kwargs)
if rtype == 'flux':
# In this case flux means really flux
flux_reddened = flux / 10**(reddeningMagnitude * ebv / 2.5)
np.seterr(**old_settings)
return flux_reddened
elif rtype == 'mag':
# In this case flux means actually a magnitude
magnitude = flux
magnitude_reddened = magnitude + reddeningMagnitude * ebv
np.seterr(**old_settings)
return magnitude_reddened
def redden(flux,wave=None,photbands=None,ebv=0.,rtype='flux',law='cardelli1989',**kwargs):
"""
Redden flux or magnitudes
The reddening parameters C{ebv} means E(B-V).
If it is negative, we B{deredden}.
If you give the keyword C{wave}, it is assumed that you want to (de)redden
a B{model}, i.e. a spectral energy distribution.
If you give the keyword C{photbands}, it is assumed that you want to (de)redden
B{photometry}, i.e. integrated fluxes.
@param flux: fluxes to (de)redden (magnitudes if C{rtype='mag'})
@type flux: ndarray (floats)
@param wave: wavelengths matching the fluxes (or give C{photbands})
@type wave: ndarray (floats)
@param photbands: photometry bands matching the fluxes (or give C{wave})
@type photbands: ndarray of str
@param ebv: reddening parameter E(B-V)
@type ebv: float
@param rtype: type of dereddening (magnituds or fluxes)
@type rtype: str ('flux' or 'mag')
@return: (de)reddened flux/magnitude
@rtype: ndarray (floats)
"""
if photbands is not None:
wave = filters.get_info(photbands)['eff_wave']
old_settings = np.seterr(all='ignore')
wave, reddeningMagnitude = get_law(law,wave=wave,**kwargs)
if rtype=='flux':
# In this case flux means really flux
flux_reddened = flux / 10**(reddeningMagnitude*ebv/2.5)
np.seterr(**old_settings)
return flux_reddened
elif rtype=='mag':
# In this case flux means actually a magnitude
magnitude = flux
magnitude_reddened = magnitude + reddeningMagnitude*ebv
np.seterr(**old_settings)
return magnitude_reddened
def get_law(name,norm='E(B-V)',wave_units='AA',photbands=None,**kwargs):
"""
Retrieve an interstellar reddening law.
Parameter C{name} must be the function name of one of the laws defined in
this module.
By default, the law will be interpolated on a grid from 100 angstrom to
10 micron in steps of 10 angstrom. This can be adjusted with the parameter
C{wave} (array), which B{must} be in angstrom. You can change the units
ouf the returned wavelength array via C{wave_units}.
By default, the curve is normalised with respect to E(B-V) (you get
A(l)/E(B-V)). You can set the C{norm} keyword to Av if you want A(l)/Av.
Remember that
A(V) = Rv * E(B-V)
The parameter C{Rv} is by default 3.1, other reasonable values lie between
2.0 and 5.1
Extra accepted keywords depend on the type of reddening law used.
Example usage:
>>> wave = np.r_[1e3:1e5:10]
>>> wave,mag = get_law('cardelli1989',wave=wave,Rv=3.1)
@param name: name of the interstellar law
@type name: str, one of the functions defined here
@param norm: type of normalisation of the curve
@type norm: str (one of E(B-V), Av)
@param wave_units: wavelength units
@type wave_units: str (interpretable for units.conversions.convert)
@param photbands: list of photometric passbands
@type photbands: list of strings
@keyword wave: wavelength array to interpolate the law on
@type wave: ndarray
@return: wavelength, reddening magnitude
@rtype: (ndarray,ndarray)
"""
#-- get the inputs
wave_ = kwargs.pop('wave',None)
Rv = kwargs.setdefault('Rv',3.1)
#-- get the curve
wave,mag = globals()[name.lower()](**kwargs)
wave_orig,mag_orig = wave.copy(),mag.copy()
#-- interpolate on user defined grid
if wave_ is not None:
if wave_units != 'AA':
wave_ = conversions.convert(wave_units,'AA',wave_)
mag = np.interp(wave_,wave,mag,right=0)
wave = wave_
#-- pick right normalisation: convert to A(lambda)/Av if needed
if norm.lower()=='e(b-v)':
mag *= Rv
else:
#-- we allow ak and av as shortcuts for normalisation in JOHNSON K and
# V bands
if norm.lower()=='ak':
norm = 'JOHNSON.K'
elif norm.lower()=='av':
norm = 'JOHNSON.V'
norm_reddening = model.synthetic_flux(wave_orig,mag_orig,[norm])[0]
logger.info('Normalisation via %s: Av/%s = %.6g'%(norm,norm,1./norm_reddening))
mag /= norm_reddening
#-- maybe we want the curve in photometric filters
if photbands is not None:
mag = model.synthetic_flux(wave,mag,photbands)
wave = filters.get_info(photbands)['eff_wave']
#-- set the units of the wavelengths
if wave_units != 'AA':
wave = conversions.convert('AA',wave_units,wave)
return wave,mag
def get_law(name, norm='E(B-V)', wave_units='AA', photbands=None, **kwargs):
"""
Retrieve an interstellar reddening law.
Parameter C{name} must be the function name of one of the laws defined in
this module.
By default, the law will be interpolated on a grid from 100 angstrom to
10 micron in steps of 10 angstrom. This can be adjusted with the parameter
C{wave} (array), which B{must} be in angstrom. You can change the units
ouf the returned wavelength array via C{wave_units}.
By default, the curve is normalised with respect to E(B-V) (you get
A(l)/E(B-V)). You can set the C{norm} keyword to Av if you want A(l)/Av.
Remember that
A(V) = Rv * E(B-V)
The parameter C{Rv} is by default 3.1, other reasonable values lie between
2.0 and 5.1
Extra accepted keywords depend on the type of reddening law used.
Example usage:
>>> wave = np.r_[1e3:1e5:10]
>>> wave,mag = get_law('cardelli1989',wave=wave,Rv=3.1)
@param name: name of the interstellar law
@type name: str, one of the functions defined here
@param norm: type of normalisation of the curve
@type norm: str (one of E(B-V), Av)
@param wave_units: wavelength units
@type wave_units: str (interpretable for units.conversions.convert)
@param photbands: list of photometric passbands
@type photbands: list of strings
@keyword wave: wavelength array to interpolate the law on
@type wave: ndarray
@return: wavelength, reddening magnitude
@rtype: (ndarray,ndarray)
"""
#-- get the inputs
wave_ = kwargs.pop('wave', None)
Rv = kwargs.setdefault('Rv', 3.1)
#-- get the curve
wave, mag = globals()[name.lower()](**kwargs)
wave_orig, mag_orig = wave.copy(), mag.copy()
#-- interpolate on user defined grid
if wave_ is not None:
if wave_units != 'AA':
wave_ = conversions.convert(wave_units, 'AA', wave_)
mag = np.interp(wave_, wave, mag, right=0)
wave = wave_
#-- pick right normalisation: convert to A(lambda)/Av if needed
if norm.lower() == 'e(b-v)':
mag *= Rv
else:
#-- we allow ak and av as shortcuts for normalisation in JOHNSON K and
# V bands
if norm.lower() == 'ak':
norm = 'JOHNSON.K'
elif norm.lower() == 'av':
norm = 'JOHNSON.V'
norm_reddening = model.synthetic_flux(wave_orig, mag_orig, [norm])[0]
logger.info('Normalisation via %s: Av/%s = %.6g' %
(norm, norm, 1. / norm_reddening))
mag /= norm_reddening
#-- maybe we want the curve in photometric filters
if photbands is not None:
mag = model.synthetic_flux(wave, mag, photbands)
wave = filters.get_info(photbands)['eff_wave']
#-- set the units of the wavelengths
if wave_units != 'AA' and photbands is not None:
wave = conversions.convert('AA', wave_units, wave)
return wave, mag
