Satellite observations of the nitric oxide nightglow

The NO δ‐bands have been observed photometrically by the ultraviolet telescope onboard the TD‐1 ESRO satellite. The maximum intensity for the system is about 220 R, in good agreement with a previous rocket measurement. Assuming that the excitation is due to the N + O → NO(C²Π, v=0) preassociation, we used the observed profile to derive the atomic nitrogen density distribution. We found a peak of about 9 × 10 7 cm −3 at about 180 km. A comparison is made with theoretical predictions, and some implications of such a high N( 4 S) density are discussed.