Observations of the November 1995 Sun crossing of the Saturn ’ s ring-plane made with the 3.6m CFH telescope , using the UHAO adaptive optics system , are presented here .
We report the detection of four arcs located in the vicinity of the F ring .
They can be seen one day later in HST images .
The combination of both data sets gives accurate determinations of their orbits .
Semi-major axes range from 140 020 km to 140 080 km , with a mean of 140 060 \pm 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 arc observed at the same epoch in HST images .