Secular Variation of the Flux Density of the Radio Source Cassiopeia A

Abstract

Högbom and Shakeshaft1 have recently presented evidence for a secular variation of the intensity of radio emission from the source Cassiopeia A. Their observations, made at a frequency of 81.5 Mc./s. over a period of 12 years, suggest that the flux density of Cassiopeia A relative to that of Cygnus A is decreasing at a rate of about 1 per cent per annum. This type of measurement may be sensitive to unknown systematic instrumental effects, and the importance of the result makes independent confirmation desirable.

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References

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    Högbom, J. A., and Shakeshaft, J. R., Nature, 189, 561 (1961).

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    Westerhout, G., B.A.N., 14, 215 (1958).

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    Mezger, P. G., Z. Astrophys., 46, 234 (1958).

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    Heeschen, D. S., Astrophys. J. (in the press).

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    Hagen, J. P., McClain, E. F., and Hepburn, N., Proc. Inst. Rad. Eng., 42, 1811 (1954).

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HEESCHEN, D., MEREDITH, B. Secular Variation of the Flux Density of the Radio Source Cassiopeia A. Nature 190, 705–706 (1961). https://doi.org/10.1038/190705a0

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