Balloonborne measurements of energetic dayside electron precipitation at South Pole Station

There is relatively little published information about energetic (x 20 kiloelectronvolt) electron precipitation in the high-latitude dayside auroral zone. The emphasis in statistical studies has been on energies of 20 kileolectronvolts or less (Hardy, Gussenhoven, and Holeman 1985). The authors will present data which suggest that energetic electron precipitation is a significant phenomenon even at invariant (i.e., magnetic) latitudes as high as 75 degrees, the invariant latitude of South Pole Station. Between 15 December 1985 and 16 January 1986, the University of Houston and the University of Maryland used balloon-borne sensors to measure bremsstrahlung X-rays (from precipitating electrons) and electric fields at South Pole Station. In this paper, they present bremsstrahlung data for 2 and 3 January 1986