Direct measurement of auroral electrons of low energies

The flux of precipitating electrons in the northern auroral zone has been measured with scintillation-type detectors aboard a polar orbiting satellite. The total preciptated energy and spectrums of electrons with energies greater than 180 ev were observed on each of 6 traversals of the auroral zone over distances of hundreds of kilometers. In most instances the dominant contribution to the preciptated flux was from electrons with energies of less than 10 kev. Spectral measurements were made 128 times per second (every 63 meters), and rapid fluctuations in both total precipitated energy and spectral shape were observed.