def get_dust_attn_curve_d1(wave,d1=1.0):
    """ Calculate birth cloud dust attenuation curve
    Parameters
    ----------
    wave: Float or 1-D Array
        Wavelengths (Angstroms) at which attenuation curve should be evaluated
    d1: Float
        Birth cloud dust optical depth
    
    Returns
    -------
    Birth dust attenuation curve at given wavelength(s); inverse law from Charlot+Fall 00 assumed
    """
    return d1*(wave/5500.0)**(-1)