Observations of the event of May 16, 1981 in optical light and in kilometric radio emission

We present the results of Prognoz-8 observations of radio emission in the range 2160-540 kHz for the event of May 16, 1981. We pick out active periods on the basis of the optical data, and we compare radio bursts with activity phenomena observed in Halpha-filtergrams during preflare, maximum, and post-maximum phases of the flare. In the explosive phase, at the time when two ribbons of emission form, we observed a burst of radio emission similar to type III burst, with a rapid frequency drift. Estimates of the speed of the excitation agent yield the value V = 0.72c. We propose that at great heights (R = 8-20 R.), particles break out of the shockfront. During the post-maximum period, when arched structures existed in the flare, we observeno special phenomena in kilometric radiation, apart from small noise bursts