On 13 March 2010 an unusually long duration event was observed by radio spectrographs onboard the STEREO-B and Wind spacecraft .
The event started at about 13:00 UT and ended at approximately 06:00 UT on 14 March .
The event presents itself as slow drifting , quasi-continuous emission in a very narrow frequency interval , with an apparent frequency drift from about 625 kHz to approximately 425 kHz .
Using the \inlinecite springerlink:10.1023/A:1005049730506 interplanetary density model we determined that the drift velocities of the radio source are \approx 33 km s ^ { -1 } and \approx 52 km s ^ { -1 } for 0.2 and 0.5 times the densities of Leblanc model , respectively with a normalization density of 7.2 cm ^ { -3 } at 1AU and assuming harmonic emission .
A joint analysis of the radio direction finding data , coronograph white-light observations and modeling revealed that the radio sources appear to be localized in regions of interaction with relatively high density and slow solar wind speed .