Conjugate Point Observations at a Variety of High Geomagnetic Latitudes

This paper summarizes the present status of some studies of the ionospheric absorption of cosmic noise observed at geomagnetically conjugate points. These studies are being carried out by the Central Radio Propagation Laboratory with the cooperation of various other agencies. One series of observations, made during a brief period in December 1961 and January 1962, is believed to represent the first attempt in which observing stations were deliberately set up at locations known to be conjugate beforehand. For this experiment, sites near Quebec City, Canada, were used simultaneously with a station now known as Eights on the Antarctic continent. The detailed results from this study, which are summarized below, will be published elsewhere in the near future (Little, Schiffmacher, Chivers and Sullivan, in preparation). Another conjugate point study became possible when it was discovered, after a year of riometer observations at the Russian base Mirnyy in Antarctica during 1961, that there had been a riometer in operation at Longyearbyen, Spitsbergen, at the same time, and that Longyearbyen and Mirnyy are almost conjugate locations. Some of the results of this study have been published (Gillmor, 1963; Gillmor and Hargreaves, 1963) and one paper is in the press (Eriksen, Gillmor and Hargreaves). A summary of the principal findings appears below. This paper is concluded with a description of the present program which involves three pairs of conjugate points, together with a brief mention of some of the preliminary results of this work.