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


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.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.


  1. 1

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

  2. 2

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

  3. 3

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

  4. 4

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

  5. 5

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

Download references

Author information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

HEESCHEN, D., MEREDITH, B. Secular Variation of the Flux Density of the Radio Source Cassiopeia A. Nature 190, 705–706 (1961).

Download citation

Further reading


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.