S/2004 S 3

S/2004 S 3 is the designation of an object seen orbiting Saturn just beyond the farther part of the F ring on 21 June, 2004. It was first seen by Carl Murray of the Cassini Imaging Science Team Archived 2011-05-20 at the Wayback Machine in pictures taken by the Cassini-Huygens probe on June 21, 2004,[3] and announced on September 9, 2004.[5]

S/2004 S 3

Discovery image of S/2004 S 3
Discovery
Discovered by	Carl Murray Cassini Imaging Science Team
Discovered on	21 June, 2004
Orbital characteristics
Semimajor axis	140,100 − 140,600 km[1][2][3]
Eccentricity	< 0.002 [4]
Orbital period	0.62 d
Inclination	close to zero
Is a satellite of	Saturn
Physical characteristics
Mean diameter	3–5 km
Rotation period	probably synchronous
Axial tilt	unknown
Albedo	unknown
Atmosphere	none

Even though later astronomers tried to find it again, it has not been reliably seen since. Notably, an imaging sequence covering an entire orbital period at 4 km resolution taken on 15 November, 2004 failed to find the object. This suggests that it was a clump of material that had disappeared by that time.[1]

Another object, S/2004 S 4, was seen nearby 5 hours later, but this time just inside the F Ring. Because of the different location of the second object, it was given a fresh designation, although their interpretation as a single object on a F-ring crossing orbit is also possible.[5] Such an object might also be orbiting at a bit different inclination to the F ring, thereby not actually passing through the ring material even though it was being seen both radially inward and outward of it.

If a solid object after all, S/2004 S 3 would be 3−5 km in diameter based on brightness, and might be a shepherd satellite for the farther edge of Saturn's F ring.