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An emission band between 500 and 1000 cps has frequently been recorded at the Kiruna Geophysical Observatory (geomagnetic latitude 65.3°N) by a swept frequency battery-operated analyzer. The most important characteristics of this enhanced electromagnetic radiation are the following: (1) The maximum signal strength is observed at a fixed frequency (700±100 cps). (2) The bandwidth of the emission is normally less than 500 cps. (3) The shape of the emission band is asymmetrical. The hypothesis advanced is that this emission band may be due to radiation at the gyrofrequency of protons. Propagation conditions determine the latitude where this band emission can be detected on the ground.
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Egeland et al. (1965) studied this question.
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