camelCase rather than lower_case method names (violates PEP 8)
Manual conversion between wavelengths and frequencies (may be done more concisely with astropy.units.equivalencies.spectral())
Manual conversions between fluxes and AB magnitudes (again, can be done concisely with Astropy units)
This module should not be necessary at all if we use the Astropy affiliated package, synphot, for evaluating extinction in band and converting between various equivalent flux units.
astropy.units.equivalencies.spectral())