IMAGES OF THE HOT-SPOTS IN CYGNUS-A AT 87 GHZ

We used the Berkeley-Illinois-Maryland Association array to map Cygnus A at 87 GHz with 0.'' 4 angular resolution. The hot spots at the work ing surfaces in the radio lobes show spectral index gradients from -0. 6 to -1.1 between 87 and 5 GHz, which suggests significant synchrotron aging in the hot spots. The data do not show a marked spectral break between 5 and 87 GHz, however, which suggests a continuous injection o f high-energy relativistic particles into both compact and extended ho t spots on timescales less than 3 x 10(4) yr.