Fine Structure of the Extra-terrestrial Radio Source Cygnus I

Abstract

The investigation of the nature of the intense localized sources of extra-terrestrial radio emission which were discovered in 1948 has been hampered by the technical difficulties of achieving sufficient resolution to measure their dimensions. Partial solutions of these difficulties were reached simultaneously in 1952 by independent developments at Cambridge, Jodrell Bank and Sydney^1–3, as a result of which preliminary measurements of the angular diameters of the intense sources in Cassiopeia and Cygnus were made. These measurements were not in complete agreement, particularly in the case of the Cygnus source, where the Jodrell Bank results indicated that the source might be markedly asymmetrical. During the past year the fine structure of this source has been studied in greater detail, and the present communication summarizes the results obtained.