Ultraviolet spectra between 530 and 1520 ¿ of an active auroral arc were obtained at 6.5-¿ instrumental resolution. Several new emission features are identified, including several bands of the N2 Birge-Hopefield (1,n\) progression and numerous N I multiplets, the latter being preponderant at low altitudes. The improved instrumental resolution over previous experiments in the wavelength region below 1200 ¿ allows for a partial resolution of the complex structure between 900 and 1100 ¿ reported in earlier work. The ratio of O I &lgr;1356 to N2 Lyman-Birge-Hopfield is smaller than in the dayglow at a similar altitude, and this is interpreted as evidence for a depletion of atomic oxygen in the auroral ionosphere relative to mid-latitude composition.