Initial observations of auroras by the multi-spectral auroral camera on board the Reimei satellite

The small Japanese scientific satellite Reimei was launched successfully from Baikonur Space Center into a sun-synchronous (noon-midnight meridian) polar orbit at an altitude of ∼630 km on August 23, 2005. Auroral fine structure observations have been performed by the multi-spectral auroral camera (MAC) and electron/ion spectrum analyzers (ESA/ISA) on board Reimei. The MAC is a three channel camera system used to simultaneously observe the temporal dynamics of the auroral fine structure at the wavelengths of 428 nm (N₂⁺ 1NG), 558 nm (O), and 670 nm (N₂ 1PG). Since its successful launch, Reimei has been operated continuously and produced lots of unique data on the auroral fine structures with the MAC and ESA/ISA. The initial observation data from MAC has shown the temporal dynamics of auroral fine structure, such as the vortex street, appearing in the poleward edge of the auroral oval. The significant differences in the auroral shapes between the MAC channels suggest the existence of different emission processes. Further, the height profiles of the aurora and airglow are clearly seen in the image data in the limb direction. It is expected that the various mechanisms and dynamics of auroral fine structures can be investigated by analyzing the Reimei observation data.