Auroral optical emission rates, thermal ion and electron densities, and low-energy electron fluxes were measured in an IBC I aurora by a rocket-borne payload, simultaneously with the overpass of the Atmosphere Explorer C satellite. Auroral ionization rates deduced from the rocket payload and neutral gas densities measured by an instrument on the satellite are used in a model calculation of the thermospheric manifestation of the aurora. The internal consistency of the electron and photometric measurements is demonstrated for the particle-induced emission of 3371-¿. A quenching rate of the N2(A3&Sgr;+u) state is deduced, by using the measured oxygen densities, and found to be 1.2+.7-.2¿10-10 cm3 s-1. A discrepancy between the calculated and measured ionospheric densities is discussed in terms of the abundance of nitric oxide. A discrepancy between calculated and measured low-energy electron fluxes (E<100 eV) is attributed to local plasma processes. The major source of 5577-¿ emission is found to be energy transfer from the N2(A3&Sgr;+u) state. The 6300-¿ is found to be unexplained by both electron impact on atomic oxygen and dissociative recombination of O+2.