Association of time structures of solar bursts at millimetric and at metric waves

Due to the lack of simultaneous high sensitivity/time resolution observations at mm- cm-λ and m-λ a program on such investigations has been carried out with data obtained by INPE at Itapetinga and by the Astronomical Observatory of Trieste. Preliminary results obtained by comparing mm-wave burst structures with 408, 327 and 237 MHz indicate that i) for majority of major time structures (time scales of the order of 1 sec) observed at 22 GHz bursts, corresponding type III bursts have been observed at 237 MHz, however ii) start times at mm-λ and m-λ are not often coincident at two wavelengths. These observations favour the hypothesis of (a) time dependent acceleration of energetic electrons and (b) burst emission is the response to a multiple injection of energetic electrons.