TYPE-III BURSTS OBSERVED SIMULTANEOUSLY BY WIND AND ULYSSES

We consider a period of five months when Ulysses was passing behind th e Sun as viewed from Wind and measure the low frequency cutoffs f(lo) and the local plasma frequency f(p) for 303 bursts seen by one, the ot her, or both spacecraft. The preliminary results are: 1) 68% of the bu rsts were seen on dynamic spectra of both spacecraft. 2) Only about ha lf of the bursts were simultaneously detected when Ulysses was nearly directly behind the Sun and within 20 degrees of the ecliptic, while 8 0% were detected at other times during the period of study. 3) The dis tribution of cutoffs is independent of f(p) at the spacecraft, and is statistically the same at Wind and Ulysses. 4) The correlation coeffic ient of f(lo) at Wind and Ulysses is 0.51, with many bursts (28%) havi ng the same f(lo) at the two spacecraft to within a factor of 1.12 and 50% having the same f(lo) to within a factor of 1.4; for the others f (lo) differs by up to a factor of 5. We conclude that, for many bursts the existence of an intrisic cutoff to the radiation mech: anism seem s certain, but for others propagation effects surely play a role.