This paper reports the first comprehensive spectral survey of the mesospheric airglow between 260 and 832 nm taken by the Imaging Spectrometric Observatory (ISO) on the ATLAS 1 mission. We select data taken in the spectral window between 275 and 300 nm to determine the variation with altitude of the Herzberg I bands originating from the vibrational levels v'=3 to 8. These data provide the first spatially resolved spectral measurements of the system. The data are used to demonstrate that to within an uncertainty of ¿10%, the vibrational distribution remains invariant with altitude. The deficit reported previously for the v'=5 level is not observed although there is a suggestion of depletion in v'=6. The data could be used to place tight constraints on the vibrational dependence of quenching rate coefficients, and on the abundance of atomic oxygen. ¿ American Geophysical Union 1993