Discovery of the FeO orange bands in the terrestrial night airglow spectrum obtained with OSIRIS on the Odin spacecraft

An unidentified pseudo-continuum in the 600 nm region is observed in the upper mesosphere with the limb-scanning OSIRIS imaging spectrograph on-board the Odin spacecraft. Averages of low latitude spectra at a series of tangent limb altitudes from 75 to 105 km are assembled and matched with synthetic spectra of the known night airglow emission band systems to isolate the underlying airglow continuum. The upper limit of the NO + O -> NO2* air afterglow continuum component in the observed 600 nm pseudo-continuum is estimated to be 5% at low latitudes. The spectral profile of the unidentified 600 nm residual airglow continuum is very similar to published laboratory measurements of the 'orange bands' of FeO. The volume emission rate altitude profile of this 600 nm airglow continuum, derived from averaged limb radiance profiles, is very similar in shape and in altitude to the concurrently observed Na vertical profile suggesting related source mechanisms. Citation: Evans, W.F.J., R.L. Gattinger, T.G. Slanger, D.V. Saran, D.A. Degenstein, and E.J. Llewellyn (2010), Discovery of the FeO orange bands in the terrestrial night airglow spectrum obtained with OSIRIS on the Odin spacecraft, Geophys. Res. Lett., 37, L22105, doi:10.1029/2010GL045310.