The first daytime ground-eased optical image of the aurora

Aurorae, spectacular phenomena in the polar night sky, also provide a conve nient projection of effects of complex and energetic plasma processes of th e outer magnetosphere. Much has been learned about the ionosphere and magne tosphere from night-time amoral images. However, similar imaging is extraor dinarily difficult by day, due to the overwhelming background of atmospheri cally-scattered sunlight. This is unfortunate, since many amoral plasma pro cesses may be unique to the sunlit ionosphere. A visible-light image of the aurora at lambda 630-nm wavelength was obtained from Kiruna, Sweden, at su nset on May 2, 1999, by an imaging spectrometer featuring excellent spectra l resolution and out-of-band rejection. We believe this to be the first suc h image obtained from the ground under near-daytime conditions. These obser vations were obtained as a test of principle during the development of a pr ototype instrument. We believe this technique holds great promise for futur e ground-based studies of the daylit ionosphere and magnetosphere.