Letter | Published:

Radio emission from Cyg X-3


THE most recent radio outburst of Cyg X-3 reported1,2 occurred in May, 1974. Following the announcement by Ryle1 of high activity we observed part of this outburst at 4.8 GHz with the 100-m telescope of the MPIfR at Effelsberg from May 22 to May 31, during a general survey of the Cygnus X region. The observed flux densities are summarised in Fig. 1 and have typical errors of 3% or less; the general behaviour of the sources is also sketched in for the data given by Seaquist et al.2. The observations were obtained as a flux density ratio with respect to NGC7027 from direct adjacent crosscuts, assuming a value of 5.8 Jy for NGC7027 (from refs 3 and 4). As our data did not contain very extended polarisation measurements and as they are consistent with the interpolated polarisation properties given in ref. 2, all points were brought to the mean flux density level using a polarisation angle of 70° and a linear polarisation of 4.7%.

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  1. 1

    Ryle, M., IAU Circ. No. 2670 (1974).

  2. 2

    Seaquist, E. R., et al., Nature, 251, 394–396 (1974).

  3. 3

    Higgs, L. A., Publ. Astrophys. Branch, 1, 1–454 (1971).

  4. 4

    Ross, H. N., and Seaquist, E. R., Mon. Not. R. astr. Soc., 170, 115–119 (1975).

  5. 5

    Marsh, K. A., Purton, C. R., and Feldman, P. A., Astrophys. J., 192, 697–701 (1974).

  6. 6

    Gregory, P. C., and Seaquist, E. R., Astrophys. J., 194, 715–723 (1974).

  7. 7

    Wendker, H. J., Veröff. astr. Inst. Univ. Münster, No. 10 (1966).

  8. 8

    Wendker, H. J., Astr. Astrophys., 4, 378–386 (1970).

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