Observations of long-period pulsations of electron precipitation in conjugate regions of the auroral zones

In recent years, considerable attention has been given to the conjugate aspects of various phenomena at auroral latitudes resulting from electron precipitation on the atmosphere. By and large, most of these observations have been in connection with bay-type magnetic disturbances. Only recently [Nagata et al., 1963; Chivers and Hargreaves, 1965] has consideration been extended to other, less frequent, disturbances such as slow pulsations having periods of the order of several hundred seconds. With the aim of adding to the information about conjugate aspects of these rarer events, the present letter summarizes observations of a long-period pulsation event in ionospheric absorption of cosmic radio noise at Kotzebue, Alaska (66.87°N latitude, 162.50°W longitude), and the Australian National Antarctic Research Expeditions' station at Macquarie Island (54.50°S latitude, 158.95°E longitude). Though this record shows a striking degree of simultaneity and similarity, additional features of pulsating electron precipitation are brought forward from X-ray and riometer observations outside the immediate vicinity of the conjugate regions, indicating spatial structure on a scale of a few hundred kilometers.