Quantitative Spectroscopy of the Aurora. II. The Spectrum of Medium Intensity Aurora Between 4500 and 8900 Å

Abstract

Quantitative spectra of medium intensity aurora in the 4500 to 8900 Å region at a slit width of about 10 Å are presented. By comparison with synthetically generated spectra the relative intensities of the prominent emission features have been determined, and a number of emissions of unknown origin have been identified. The emission features included in the analysis were the N2 first and second positive, Vegard–Kaplan, and infrared afterglow systems, the N2+ first negative and Meinel systems, the O2+ first negative system, the O2 atmospheric system, the OH night airglow system, the atomic line emissions, and a residual emission which was represented by a continuum. Due to the broad spectral coverage it was possible to obtain fairly complete information on the vibrational development of the brighter band systems. A number of new identifications of spectral features has led to the conclusion that in the O2 atmospheric system, bands with ν′ > 2 exist contrary to previous beliefs.