Fabry-Perot Imaging of O III lambda = 5007 Angstrom Emission in the Io Plasma Torus

In the first week of 1994 April the [O III] 5007 Å line was imaged in the Io plasma torus using the focal reducer camera of the Max-Planck-Institut für Aeronomie attached to the 2.2 m telescope of the European Southern Observatory. The emission was peaked at a Jovicentric distance of 5.8±0.2R_j at a level of 11±6 and 18±8R for the dusk and dawn ansa respectively. Generally the spatial distribution is consistent with Voyager models, but there is some evidence that the 0 111-torus is extended to larger Jovicentric distances than predicted by the model. In contrast to the spectrographic observations of Thomas (1993b) the warm sulphur torus was depressed during the time of our observations indicating that in first order there is no correlation between the presence of 0 III emission and the state of the sulphur torus.