The NII 2143 Å emission in the dayglow

Observations of the NII 2143 Å emission in the Earth's dayglow were obtained by a rocket‐borne spectrograph flown on November 9, 1981, and August 11, 1982. The ultraviolet spectra were analyzed using synthetic spectra to separate the contribution of the 2143 Å emission from the overlapping nitric oxide gamma band. The 2143 Å column emission rate profiles for both flights were quite similar with peak column emission intensities of approximately 500 Rayleighs at an altitude of 160 km. When the observed column emission rate profiles are compared with theoretical calculations, the production efficiency of this emission was found to be 0.10 ± 0.04. The 2143 Å emission varies by more than a factor of 3 over the solar cycle and therefore should be useful as an indicator of the solar EUV flux.