Detection of arcs in Saturn's F ring during the 1995 Sun ring-plane crossing

Observations of the November 1995 Sun crossing of the Saturn's ring-plane m ade with the 3.6 m CFH telescope, using the UHAO adaptive optics system, ar e presented here. We report the detection of four ar cs located in the vici nity of the F ring. They can be seen one day later in HST images. The combi nation of both data sets gives accurate determinations of their orbits. Sem i-major axes range from 140 020 km to 140 080 km, with a mean of 140 060 +/ - 60 km. This is about 150 km smaller than previous estimates of the F ring radius from Voyager 1 and 2 data, but close to the orbit of another are ob served at the same epoch in HST images.