Measurement of the 3-dimensional positions of type III bursts in the solar corona

The three-dimensional positions of type III sources in the corona are calculated on the basis of ground and spacecraft data. Simultaneous observations of the corona in visible light from Skylab make it possible to relate the apparent radio-source positions to slowly evolving coronal structures. It is found that open magnetic field lines connecting the low coronal levels to the interplanetary medium only exist in a relatively narrow region, and diverge rapidly upwards.