Simultaneous scintillation observation on 1300-MC and 3000-MC signals received during the solar eclipse of October 2, 1959

Abstract

During the total solar eclipse of October 2, 1959, and during a 10-day control period bracketing this date, measurements were made of radio signals received at frequencies of 224 Mc, 1300 Mc, and 3000 Mc. These measurements indicated that point sources on the sun, rather than the total disk, were the constant-energy sources responsible for the scintillations of the received signals. This conclusion is in agreement with the work of Kazes and Steinberg. The fact that, during the period of totality, scintillations were observed at the two higher frequencies indicated that limb sources produced the scintillations. Interferometric maps of the sun taken during this period showed plage areas at frequencies of 1420 Mc and 3300 Mc; however, at a frequency of 169 Mc, these maps showed only a relatively uniformly bright sun. In line with these findings, the recorded radio data did not show scintillations at the 224-Mc frequency but did show scintillations at the 1300-Mc and 3000-Mc frequencies. During the control period, the scintillations at 1300 Mc were well correlated in detail with those at 3000 Mc. For this frequency range, it therefore appears that the scintillation oscillations are not frequency dependent. The two sets of data were taken at different antenna apertures. The 1300-Mc data were taken on an 84-foot parabolic antenna, whereas the 3000-Mc readings were made on an 8-foot parabolic antenna, 80 feet distant from the larger unit. Thus, it appears that, for this frequency range, the mechanism is not only independent of frequency but, within the experimental limits, is also not greatly affected by the size of the antenna. The periods of the scintillations (30 seconds to 2 minutes) show that the shadow pattern is large in extent. Almost all scintillations took place when the sun was below4\degof altitude. A hypothesis is advanced that the blob structure of the troposphere, possibly at the height of the tropopause, is formed into a curved lens. The focusing of the energy through this concave lens produces the scintillations observed.