Disturbances of VLF/LF signals on Far East paths on December 27, 2004, caused by the gamma-ray flare of magnetar SGR 1806-20

摘要

VLF/LF signal variations at midlatitude, midlatitudelow-latitude, and low-latitude Far East paths related to an unusually strong gamma-ray flare from magnetar SGR 1806-20 were analyzed. Amplitude and phase anomalies were detected for all four signals received in Petropavlovsk-Kamchatski. The flare reached the Earth on December 27, 2004, at 2130:26.5 UT. Since the station signals are registered with a time resolution of 20 s, the anomalies corresponded to a much less intense oscillating "tail" rather than to an initially powerful flare impulse. It has been found that the anomaly character and value strongly differ on the considered paths.