Spatial characteristics of auroral-zone X-ray microbursts

An array of four narrowly collimated X-ray detectors, each viewing a separate part of the sky, was used to study spatial and temporal characteristics of bremsstrahlung X rays produced by energetic electron precipitation in the auroral zone. Each telescope viewed a circle of about 20-km diameter at the stopping heights of electrons (90–100 km). The telescope arrays were carried to small atmospheric depths of 2–3 g/cm² using large-volume balloons. The data revealed that the impulsive-type energetic electron precipitation events, microbursts, are not distributed uniformly in the X-ray production plane. The data further showed that each microburst precipitation region is on the average 40±14-km radius. An energetic electron precipitation event that occurred on September 16, 1965, was shaped similarly to bands aligned in the north-south direction drifting eastward with a velocity of about 250–300 m/sec. Microbursts occurred during this event, indicating that the propagating electron source region and microbursts were related.