WHISTLER WAVES OBSERVED DURING AN IN-SITU SOLAR-TYPE-III RADIO-BURST

On Dec. 24, 1996, the WIND spacecraft encountered a solar type III sou rce region at 1 AU, as indicated by a characteristic radio signature d own to less than the second harmonic of the local electron plasma freq uency, the enhancement of the electron flux at high energies and the p resence of electrostatic noise at the local plasma frequency. During t his interval, electromagnetic wave activity was recorded below the ele ctron cyclotron frequency, by the Time Domain Sampler of the WAVES ins trument. Analysis suggests that the observed waves are whistler waves, propagating, approximately parallel or antiparallel to the interplane tary magnetic field, in the plasma frame.