Directivity of non-thermal X-ray emission from solar flares

An attempt has been made in the present work to reveal the directivity of solar non-thermal X-ray emission using the data obtained from the Prognoz and Explorer satellites. The frequency of occurrence of X-ray bursts and the mean intensities of the emission are studied as a function of distance from the central meridian. The most complete statistics have been obtained for the 4–24 keV X-ray bursts for the period 1970–1973. The X-ray burst frequency of occurrence normalized to the corresponding H flare frequency increases towards the solar limb. During the studied period this trend is more pronounced to the east than to the west. Distributions of the mean intensities of X-ray bursts are very similar to those of the frequency of occurrence of X-ray bursts; the effect is more noticeable for the low intensity bursts. The effect of the east-west asymmetry for H flares has been found to vary in magnitude and direction during the 20th solar activity cycle.