Multipoint Observations of Solar Type III Radio Bursts from STEREO and Wind

The twin STEREO and the Wind spacecraft make remote multipoint measurements of interplanetary radio sources of solar origin from widely separated vantage points. One year after launch, the angular separation between the STEREO spacecraft reached 45A degrees, which was ideal for locating solar type III radio sources in the heliosphere by three-spacecraft triangulation measurements from STEREO and Wind. These triangulated source locations enable intrinsic properties of the radio source, such as its beaming characteristics, to be deduced. We present the first three-point measurements of the beaming characteristics for two solar type III radio bursts that were simultaneously observed by the three spacecraft in December of 2007 and in January of 2008. These analyses suggest that individual type III bursts exhibit a wide beaming pattern that is approximately beamed along the direction tangent to the Parker spiral magnetic field line at the source location.