Pii: 0032-0633(73)90032-9

Absfract-Stetlar ultraviolet light near 1SOOA is attenuated in the Earth’s upper atmosphere due to strong absorption in the Schumarm-Runge continuum of molecular oxygen. The intensity of stars in the Schumann-Runge continuum region has been monitored by the University of Wisconsin stellar photometers aboard the OAO-2 satellite durin ‘I, occultation of the star by the Earth’s atmosphere. These data have been used to determine t e molecular oxygen number density P refile at the occultation tangent point. The results of 14 stellar occultations obtained in ow and middle iatitudes are presented giving the night-time vex&a1 number density profile of molecular oxygen in the 140-200 km region. In general, the measured molecular oxygen number density is about a factor of 2 lower than the number densities predicted by the CZZ&4 1965 model. Also, the number density at a given height appears to decrease with decreasing solar activity. Measurements taken at low latitudes during the August 1970 geomagnetic storm showed a decrease in the molecular oxygen number density at a given height several days after the peak of the storm followed by a slow recovery to pre-storm densities. 1. INTRODUC’FION