Package: extinction-coefficient
extinction_coefficientextinction_coefficient is a astronomy Python package to provideempirical extinction or reddening coefficientsfrom far-ultraviolet (UV) to the mid-infrared (IR).(Zhang & Yuan, 2022)For a given banda, the extinction coefficient is defined as E(a)/E(B-V), i.e. extinction inaband relative to E(B−V);
Similarly, for a given colora-b, the reddening coefficient is defined as E(a-b)/E(B-V).Our coefficients are mostly valid in the extinction range of 0-0.5 mag and the temperature range
of 4000-10000 K. But note that the temperature range varies depending on the band. No extrapolation
for out-of-range input values, but rather assignment of boundary values.Available photometric surveys and passband namesGALEX passbands: "FUV", "NUV";Pan-STARRS 1 passbands: "g", "r", "i", "z", "y";SDSS passbands: "u'", "g'", "r'", "i'", "z'";Gaia DR3 passbands: "BP", "G", "RP";2MASS passbands: "J", "H", "Ks";WISE passbands: "W1", "W2", "W3", "W4".How to InstallUsing pip# from PyPI (recommmand)pipinstallextinction_coefficient# from the master trunk on the repository, considered developmental codepipinstallgit+https://github.com/vnohhf/extinction_coeffcient.gitFrom sourceextinction_coefficient can be installed from the source code after downloading it from the git repo (https://github.com/vnohhf/extinction_coeffcient/):python setup.py installQuick StartTo get a single value extinction or reddening coefficients obtained when temperature and extinction are not considered, just put mode = 'simple':fromextinction_coefficientimportextinction_coefficientextinction_coefficient('g',mode='simple')extinction_coefficient('BP-RP',mode='simple')extinction_coefficient(["BP-RP","FUV-g"],mode='simple')To obtain extinction or reddening coefficients for (a group of) specific Teff and E(B-V):Band='BP'EBV=0.3Teff=[5000,6000]extinction_coefficient(Band,EBV=EBV,Teff=Teff)Band=np.array(["BP-RP","FUV-g","y-H","u'-W2"])EBV=[0.1,0.1,0.3,0.5]Teff=5500extinction_coefficient(Band,EBV=EBV,Teff=Teff)If Teff is unknown in advance, the observed (BP-RP) color can be entered as a substitute. This program first makes a rough reddening correction to the observed (BP-RP) and then converts them to Teff using an empirical polynomial relationship between intrinsic color (BP-RP)0 and Teff. This allows the exact reddening factor to be obtained using Teff, and then the procedure iterates once.Band=["BP-RP","FUV-g","i'-z'"]EBV=[0.1,0.3,0.5]BP_RP=np.array([0.3,0.6,1.2])extinction_coefficient(Band,EBV=EBV,BP_RP=BP_RP)APIextinction_coefficient(Band,EBV=None,BP_RP=None,Teff=None,mode='func')

Args:
    Band: str or array-like, shape (n, )
            The passband or color index. If color index are entered, '-' need to be used to connect 
            the two passband name strings (e.g. "BP-RP"). There support GALEX passbands: "FUV", "NUV"; 
            Pan-STARRS 1 passbands: "g", "r", "i", "z", "y"; 
            SDSS passbands: "u'", "g'", "r'", "i'", "z'";
            Gaia DR3 passbands: "BP", "G", "RP";
            2MASS passbands: "J", "H", "Ks";
            WISE passbands: "W1", "W2", "W3", "W4";
            
    EBV: float or array-like, shape (n, ), optional
            The E(B-V), in magnitude.
    
    BP_RP: float or array-like, shape (n, ), optional
            The observed (BP-RP) color index.
    
    Teff: float or array-like, shape (n, ), optional
            The effective temperature, in Kelvins.
            
    mode: {'func', 'simple'} (default: 'func')
            The calculate mode of extinction or reddening coefficients. Possible values:
            'func': interpolation results on functions of Teff and E(B-V).
            'simple': single value coefficients obtained when temperature and extinction are not considered.

Returns: float or array-like, shape (n, )
    Empirical extinction or reddening coefficients. Has the largest shape as the input obj:`Band`, obj:`EBV`, 
    obj:`BP_RP`, or obj:`Teff`.