The HILAT vacuum ultraviolet auroral imager.

An integral part of the requirements of the HILAT mission was to produce imagery in full daylight of the earth's auroral activity, the aurora borealis, with a selectable 30 Å spectral window in the vacuum ultraviolet spectrum ranging from 1100 to 2078 Å and a dynamic range from 80 to 10⁵ Rayleighs. This resulted in the design of the multimode instrument called the Auroral Ionospheric Mapper. It functioned primarily as an imager with secondary operation as a photometer at preselected wavelengths with the same spectral window or as a spectrometer scanning the full spectral range.