The solar backscattered ultraviolet spectral radiometer on the Nimbus 7 satellite routinely measures fluorescence emissions from the nitric oxide (1, 4) gamma band that are imposed on the large Rayleigh-scattered signal in the wavelength range 255--256 nm. The gamma band feature, when isolated from the background radiance, provides information on the seasonal and latitudinal variations in the nitric oxide column abundance over the altitude region from 40 to 45 km upward through the thermosphere. At latitudes from 30¿ to 45¿ in the northern hemisphere the measurements show an annual cycle with maximum nitric oxide abundance in summer. The southern hemisphere pattern is qualitatively similar to this, although the amplitude of the seasonal variation is substantially smaller. The most prominent feature of the data base is a large maximum in nitric oxide emission that develops poleward of 45¿ latitude in both hemispheres during late autumn and early winter. These maxima dissipate rapidly as spring approaches and are no longer evident in the data for northern hemisphere March and southern hemisphere September.