Very-large-array observations of a complex gradual solar burst at 6 CM wavelength

The authors present a 6 cm VLA observation of a burst from a solar active region. The burst shows a normal impulsive rise-and-fall superimposed on a gradual component. The peak brightness temperature of the burst remains relatively constant, and the flux variations are due to changes in the source structure. It appears as though an arcade of loops is gradually heated or filled with hot plasma. The burst is weakly polarized but unipolar; the authors investigate the possible reasons for this structure. Depolarization of optically thin emission due to twisted magnetic fields within the source can produce significant depolarization, but is probably not active in this event. Instead, it is suggested that the flare emission is optically thick and that hot overlying material preferentially absorbs one polarization.