Apparent Intensity Variations of the Radio Source Hydra?A

Abstract

SummaryThis paper describes the results of a detailed study of the flux density of the discrete radio source, Hydra-A. Over a period of 12 months, approximately 200 measurements of the Hydra-A intensity were compared with a similar number of observations on other strong sources. It was concluded that the observed flux density of Hydra-A is much more variable than that of these other sources, although no periodic changes have yet been detected. Possible mechanisms for the observed intensity changes are discussed.

From the Solar Corona to Clusters of Galaxies: The Radio Astronomy of Bruce Slee

“…Bolton, Stanley and Slee, in various authorship combinations, then prepared three different papers on aspects of this survey, but often incorporating data from the earlier Dover Heights source surveys (see Bolton, Stanley and Slee, 1953;and Bolton, Westfold, Stanley and Slee, 1954). Slee also made a special study of the intensity variations exhibited by the Hydra A source, and this was written up as his first solo paper (Slee, 1955;c.f. Bolton and Slee, 1957).…”

“…One of the early results to come from the Dover Heights radio stars project was the discovery that variations in the intensity of Cygnus-A and other 'radio stars' were not intrinsic to the source itself but were associated with scintillations (Bolton and Slee, 1957;Bolton, Slee and Stanley, 1953;Slee, 1955), and this was to open up a whole new area of investigation that Slee would pursue while based at the Fleur field station. An example of scintillations on the interferometer record of Cygnus A on 1948 May 19 is shown in Figure 7.…”