Electrons at low altitudes: a difficult background problem for soft x-ray astronomy

Quasi-trapped and precipitating electrons have been observed with rocket- borne x-ray asironomy detectors in the altitude range 150 to 500 km. Because the flights occurred at low magnetic latitudes the electrons were unexpected. Data from many flights are combined to derive altitude dependence, an average electron spec, trum, and variation with solar activity. Development of electronrejecting collimators is discussed, and laboratory and flight data on these collimators are presented. (auth