Balloon measurements of energetic electron precipitation in the vicinity of South Pole Station

The first balloon measurements of electron precipitation over the geographic south pole were made between 15 December 1985 and 16 January 1986 with launches from South Pole Station. This work was part of a University of Houston/University of Maryland campaign. The University of Houston measured electric fields on all eight payloads and bremsstrahlung X-rays on four, while the University of Maryland measured X-rays on the other four payloads. This article emphasizes data on precipitating electrons deduced from X-ray measurements made by the University of Maryland on 2 and 3 January, 1986, a geomagnetically active period. The instrument was identical to that used in previous campaigns, consisting of a sodium-iodide scintillator, 7.6 centimeters in diameter, mounted integrally with a suitable photomultiplier. The scintillator had a 25-micron beryllium window and was otherwise unshielded. Energies from 25 to 500 kiloelectronvolts were measured in seven differential channels and an integral channel