High Resolution Observations of Cygnus A at 2.7 GHz and 5 GHz

Observations of Cygnus A (3C 405) have been made with the One-mile telescope operating at frequencies of 2.7 and 5 GHz, where the beamwidths are $$12^{\prime\prime} \times 19^{\prime\prime} \,\text{and} \,6^{\prime\prime}.5 \times 10^{\prime\prime}$$ arc respectively. The maps obtained show that each component consists of a compact region of high surface brightness with an extension of decreasing brightness running towards the optical galaxy. A comparison with earlier observations shows little variation of structure with frequency except at frequencies < 200 MHz; at low frequencies there is a relatively greater contribution from the extensive features, and the change in the distribution may be associated with the change in spectral index of the source in this frequency range. The observed brightness distribution of the components supports the suggestion of De Young & Axford (1967) that the plasma clouds are contained by interaction with the intergalactic medium.