WIND-ULYSSES SOURCE LOCATION OF RADIO EMISSIONS ASSOCIATED WITH THE JANUARY 1997 CORONAL MASS EJECTION

We investigate the 3-D source location of interplanetary type II-like radio bursts from observations involving two spacecraft. Uncommon type II radio emissions were observed simultaneously on 8 January 1997 by the Wind and Ulysses spacecraft and are believed to be associated with the Interplanetary Coronal Mass Ejection detected on 6 - 7 January by the LASCO coronagraph on the SOHO spacecraft and on 10 - 11 January b y Wind. Ulysses was located about 4.73 AU from the Sun at 25.6 degrees N ecliptic latitude and 45.1 degrees W of Earth, while Wind was in th e solar wind upstream of the Earth. The two spacecraft recorded nearly similar intensity time profiles at the common frequency of 196 kHz. B y means of radio triangulation, we locate the 3-D source region, infer ring it to be strongly deviated by several AU from the expected source between the Sun and Earth towards the solar hemisphere opposite Earth . Strong propagation effects, such as scattering and refraction, are s uggested as affecting Ulysses observations (both in apparent source si ze and direction), being due to the presence of interplanetary overden se structures of various scales. We also de duce the source location f rom the direction as measured at Wind and the difference of the arriva l times as measured at both spacecraft. From this latter approach we f ind that the source location is closer to Wind than the expected sourc e by similar to 0.2 - 0.4 AU, corresponding to an excess travel time o f similar to 0.55 - 1.44 min on the radiation path to Ulysses. The exc ess delay time is found to be about 2.6 times greater for the fundamen tal emission than for the harmonic emission, and it is found to vary ( approximately) inversely as the decay time of the intensity at Ulysses , presuming the existence of scattering.