Bursts observed at 21 CM with the Westerbork interferometer

The characteristics of two solar radio bursts observed at 21 cm with the Westerbork radio interferometer are discussed. The first burst was observed simultaneously with an optical flare of class I and was found to be composed of several sources. Of the two longest-lasting sources, one was observed to be located above the optical flare and to be completely unpolarized with intermittent appearance, and the other was observed to be completely left-hand circularly polarized, suggesting a position above the region of the positive magnetic field. The second burst was recorded simultaneously with a subflare at the position of the first burst, and was found to exhibit a strong left-hand circular polarization which split into two components with opposite polarization which then lost their polarization. The observed polarization behavior can be explained in terms of emission from a thermal source in the presence of a magnetic field.