During the geomagnetic storm of 8--9 November 1991, the Upper Atmosphere Research Satellite (UARS), orbiting at 585 km, passed through the expanded auroral zone during portions of several successive orbits. The instruments of the UARS Particle Environment Monitor (PEM) observed particle precipitation, auroral x-ray emissions,and large-scale disturbances in the geomagnetic field during this time. In this paper we present observations made by the PEM instruments during this storm and compute ionization and energy deposition rates as functions of altitude in the middle and upper atmosphere by incident electrons and positive ions in the storm interval. The suite of PEM instruments provides a systematic measurement of energetic particles and their associated x-rays over an energy range not fully covered by previous satellite missions. In this energy range the ionization and dissociation rate in the atmosphere may be inferred from the upper stratosphere to the thermosphere. The impact on the chemistry of the region may be investigated. ¿ American Geophysical Union 1993