XXX. Fluctuations in the intensity of radio waves from galactic sources

Summary It has been shown previously that the fluctuations in the intensity of radio energy from the galactic sources have a local terrestrial origin. This paper describes further observations of the two most intense sources, in the constellations of Cygnus and Cassiopeia, taken over a wide range of angles of elevation. At high angles of elevation the radio fluctuations are shown to be correlated with the occurrence of "spread" ionospheric echoes from the F region. When the sources are low on the northern horizon fluctuations are always observed; these are probably introduced by the passage of radio waves through the continuously disturbed ionospheric regions at high magnetic latitudes. Spaced receiver observations taken over base lines of 0·1, 4 and 11 km. enable the scale of the radio energy diffraction pattern across the ground to be determined.