The radio spectrum of IC 443

The distribution of the radio spectral index over the supernova remnant IC 443, derived from maps at 1.4 and 10.7 GHz, confirms the relative steepening at high frequencies of the spectrum near the brightest optical features (or an equivalent flattening elsewhere). The series of lunar occultations during 1974 will provide an opportunity for investigation of the detailed brightness distribution at lower frequencies, which may throw light on the reason for the spectral variation.