Difference image between the exposures taken at 7:11:20 (before the outburst) and 7:16:09 (after the outburst) in the UV-375 nm filter clearly showing the broad main jet and a secondary narrow filament. The red cross shows the suspected source point constructed under the assumption that the two jets originate from the same location and the ellipse gives the 2σ uncertainty. The half circles indicate the distances used for the angular radiance distributions plotted in Fig. 5.