Altitude determination of ultraviolet measurements made by the Student Nitric Oxide Explorer

The spinning motion of the Student Nitric Oxide Explorer spacecraft allows for the measurement of limb profiles of atmospheric radiation. In order to interpret the observations an accurate altitude reading is necessary. Included in the limb profile is Rayleigh-scattered solar radiation that can be used to determine altitude. The Rayleigh profile increases exponentially with decreasing altitude until the absorption due to ozone dominates the shape, producing a peak near 53 km. We use the Rayleigh scattering peak to register the measured profile in altitude for each ultraviolet spectrometer observation. A single-scattering radiance model is developed and used to provide an altitude-dependent shape of the Rayleigh profile. The attitude registration is done by correlating the data to the model for each measured profile. By systematically shifting the measured profile in small increments and filling the shifted profile to the model the quality of the fit is determined. The shifted profile that best correlates with the model profile determines the correct shift in altitude to 1.5 km precision.