The ultraviolet dayglow at solar maximum: 2. Photometer observations of N₂ second positive (0, 0) band emission

The N 2 second positive, C ³Π u ‐ B ³Π g , (0, 0) band dayglow emission at 3371 Å was observed during solar maximum with a rocket‐borne filter photometer, simultaneously with spectrometer observations of the far ultraviolet N 2 and O dayglow spectrum. Modeling of the near ultraviolet dayglow spectrum indicates that the instrument also detected the N 2 Vegard‐Kaplan, A ³Σ u + ‐ X ¹Σ g + , (0, 9) band. A spectral synthesis of these bands is used to derive emission intensities. The intensities are combined with the results of the analysis of the far UV observations reported by Meier et al. (this issue) to determine the topside neutral temperature and photoelectron flux. The effects of varying the reaction coefficient k 0 for quenching of the υ′ = 0 level of the N 2 A ³Σ u + state are discussed. For k 0 = 2.4×10 −11 the derived g factor for C ³Π u production is 4.4×10 −8 s −1 at an altitude of 290 km, whereas for k 0 = 2×10 −10 it is 5.4×10 −8 s −1 . A synthetic spectrum of these two band systems in the wavelength region between 3000 and 4000 Å is presented.