Balloon observations of auroral X-rays at Esrange, Sweden and related phenomena

Balloon observations of auroral X-rays using different detector systems were carried out twice over Esrange, Sweden, in November and December 1982,in order to examine spatial and temporal characteristics of the energetic component of auroral electrons. One detector is a telescope system consisting of four scintillation counters whose fields of view are different with each other as well as with the viewing directions. It is shown from the first flight carrying the telescope system that a limited illuminating region of auroral X-rays coincides with that of visual aurora. The other is the so-called pinhole camera and a shot of X-ray image detected by a thin NaI (T1) crystal is viewed by a microchannel plate photomultiplier tube (MCP PMT) with 4×4 anodes. The second flight was made for simultaneous observations by three kinds of payloads of the MCP PMT system, a subsidiary X-ray energy counter and a VLF wave receiver. The balloon did not encounter good activity of aurora enough for X-ray image-formings by the MCP PMT system during the ceiling flight, but the other two detectors revealed the first on-board evidence of the auroral X-ray event well associated with abrupt absorption of VLF emissions