The Structure of Compact Radio Sources at 606 MHz

Citation

Purcell, George Harber (1973) The Structure of Compact Radio Sources at 606 MHz. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/8jjw-z848. https://resolver.caltech.edu/CaltechETD:etd-08212008-100027

Abstract

Long-baseline interferometry has been used to study the structure of thirteen compact radio sources at 606 MHz. The baseline was 3324 kilometers long and nearly east-west in orientation, so that the maximum angular resolution was about a hundredth of a second of arc for each source. There were two series of observations, made on June 29 to July 1, 1971, and February 3 to 6, 1972. For most of the sources observed in each session, the correlated flux was measured from ten to forty times over a wide range of hour angle, with a standard error for each measurement of about 0.12 flux unit. A few sources were observed less often. Simple source models were then fitted to the data and compared to the models proposed by other observers. The data for most of the sources were found to be consistent with models containing an elliptical halo concentric with an unresolved core. 3C 147, 3C 273, and 3C 279 appear to be more complicated, however. The observations of 3C 84, 3C 279, and 3C 345 also show evidence of weak structure at relatively large distances from the strong central components. P1345+12 and CTD 93 were observed only in the first session, and 3C 120 and 3C 286 only in the second session. CTA 21, 3C 84, 3C 147, 3C 273, 3C 279, 3C 345, 3C 380, CTA 102, and 3C 454.3 were observed in both sessions, and all but CTA 21 and 3C 380 gave strong evidence of changes in flux or structure during the interim. These changes appear to be intrinsic to the sources, and not the result of instrumental effects or scintillation phenomena.

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