On May 31, 1992, a rocket payload equipped with 10 airglow photometers was launched from the Alcaˆntara Launch Center in Northern Brazil. The payload was designed to measure sodium, hydroxyl, atomic, and molecular oxygen airglow emissions, in addition to electron density and temperature. At the time of launch, a sodium lidar was operated at the same site, giving vertical profiles of atmospheric sodium density. The measured vertical profiles of the Na D line emission and atomic sodium density are remarkably similar, with sharp boundaries at 81 km and 99 km. On the assumption that the Chapman mechanism is responsible for the Na D emission, the measurements imply an almost constant ozone density of 4¿107 cm-3 between 87 and 99 km. The unexpectedness of this height independent ozone concentration suggests that our understanding of the sodium excitation mechanism might be inadequate. ¿ American Geophysical Union 1993