A High-Frequency Study of Cygnus A,

Measurements at 8300 and 9600 MHz are combined to map the distribution of total radiation across Cygnus A with a beam of half-power width about 20 seconds EW x 30 SECONDS NS. Steep brightness contours are noted on the outer edges and more gradual inner extensions towards the optical galaxy. The brightest peaks within each radio component have flatter spectra than the rest of the source. The distributions of linearly polarized radiation at both 8300 and 9600 MHz are also mapped. Nearly everywhere in the source the degree of polarization at 9600 MHz exceeds that at 8300 MHz. The rotation measures vary more or less systematically across Cygnus A from a very large negative value at the following edge to a positive value on the preceding edge. Author