Non-stormtime injection of energetic particles into the slot-region between Earth's inner and outer electron radiation belts as observed by STSAT-1 and NOAA-POES

[1] The slot-region between Earth's inner and outer electron radiation belts was observed on 24 February 2004 by the satellite STSAT-1 to be populated by quasi-trapped electrons of energy 100-400 keV. This injection lasted for several hours and took place during a non-stormtime substorm. This appears to be the first observation of a slot-region electron injection that did not occur during a geomagnetic storm. We also report multi-instrument observations of this event from NOAA-POES and CPMN magnetic observatories, and we consider physical mechanisms that may account for the phenomenon.