R R Anderson and J D Scudder, The University of Iowa, Department of
Physics and Astronomy, Iowa City, IA 52242, USA, Phone: 319-335-1924,
FAX: 319-335-1753, e.mail: roger-r-anderson@uiowa.edu
H Matsumoto, Radio Atmospheric Science Center, Kyoto University, Uji,
Kyoto 611, Japan
W Imhof, D Chenette, J Mobilia, Lockheed-Martin Palo Alto Research
Laboratory, Dept. 91-20, Bldg. 252, Palo Alto, CA 94394
M Walt, STAR Laboratory, Stanford University, Stanford, CA 94305
G Rostoker, Department of Physics, University of Alberta, Edmonton,
Alberta, Canada T6G 2Jl
S Kokubun, Solar Terrestrial Environment Laboratory, Nagoya University,
3-13 Honohara, Toyokawa, Aichi 442, Japan
D H Fairfield, NASA/Goddard Space Flight Center, Greenbelt, MD 20771
Several events have been detected in which strong burst of AKR near the local electron cyclotron frequency preceded the detection of strong bursts of 2-12 keV X-Rays from precipitating electrons by several tens of seconds. During southern hemisphere perigee passes in early 1997 of the NASA POLAR satellite, Auroral Kilometric Radiation (AKR) and precipitating electrons were measured remotely by the POLAR Plasma Wave Instrument (PWI) and X-Ray Imager (PIXIE), respectively. GEOTAIL, when near its apogee at -30 Re in the tail, detected enhancements in AKR at the same time as the POLAR AKR observations began. At nearly the same time the CANOPUS ground magnetometers, usually when located near local night, indicated the beginning of a geomagnetic disturbance. The strong X-Ray bursts which followed several tens of seconds later occurred simultaneously with the observation by POLAR of enhanced low frequency electrostatic noise. The POLAR HYDRA experiment detected inverted Vs centered on the peak of the precipitating electrons. On several occasions strong bursts of up-going ions were also observed. For some of the events, GEOTAIL detected in situ changes in the magnetic field indicating motion of the spacecraft in the plasmasheet towards the current sheet before the strong AKR and X-Ray bursts followed by movement away afterwards. Occasionally a plasmoid or flux rope was detected tens of minutes after the event. Some events were very brief. If triggering of the aurora by AKR occurs, it is evident that the magnetosphere has to be ready to respond in order for significant activity to continue. It is possible that the AKR might initially be produced by precipitating electrons that produce X-Rays below the PIXIE detectable range. We will discuss the plausible explanations for these many interesting observations.
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