Distribution of X-ray Emission from the Sun deduced from Measurements of Ionospheric Absorption

Abstract

DURING the annular solar eclipse of May 20, 1966, over parts of northern Africa and southern Europe, solar flux and ionospheric absorption measurements were made from several points along the central line of the path of the eclipse. Solar flux was measured at various frequencies in the cm and mm bands. All the data obtained during the eclipse showed characteristic variations in flux related to local active sources on the solar disk. Fig. 1 shows the distribution of local sources on the solar disk measured in Athens by Castelli on 2,695 MHz (private communication). Three sources giving an increase in flux were identified during this eclipse: one on the west limb, the second in the middle of the disk and the third on the east limb. Two sources of less importance were also identified on the north-east part of the disk.