Revised depolarization corrections for atmospheric extinction

depth of the atmosphere, based on laboratory measurements published up to 1968. They state that the uncertainty of the present calculations is mainly due to the lack of accurate de polarization data. This is true, but not in the sense they intend. First, several accurate new measurements have been pub lished since 1968.2-5 More importantly, both Fröhlich and Shaw1 and Hoyt6 err by excluding the rotational Raman contribution to the optical depth. In fact,2,3,7-9 the classical formulae for Rayleigh scattering refer to the total molecular scattering. (They also remain true for any part that includes the central line.9) Obviously, the extinction optical depth must include the Raman component, as the Raman-scattered photons have come from the incident beam, just as the un-shifted photons have. Excluding the Raman wings also ex