C. C. Porco, CICLOPS, Space Science Institute, Boulder; and the Cassini Imaging Science Team report the discovery of a satellite orbiting within the outer B ring in Saturn's rings. The satellite was seen in a single Cassini narrow-angle camera image with an exposure time of 820 ms, taken through the clear filter on July 26 (or sixteen days before Saturn's northern vernal equinox on Aug. 11), through the presence of a 36-km long shadow that it cast onto the rings. Its radial distance from the center of Saturn at the time of the observation was measured to be 117000 km. From the length of its shadow and the elevation of the sun at the time of the observation, the distance that the satellite protrudes above the rings was measured to be approximately 150 m; the inferred diameter of the satellite, assuming an orbit co-planar with the ring material, is consequently approximately 300 m.
International Astronomical Union Circular
- Pub Date:
- November 2009