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S/2004 S 3

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S/2004 S 3
S2004 S 3 - PIA06115.png
Discovery image of S/2004 S 3
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

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 in pictures taken by the Cassini-Huygens probe on June 21, 2004,[3] and announced on September 9, 2004.[5]

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.


  1. 1.0 1.1 Spitale, J. N.; et al. (2006). "The orbits of Saturn's small satellites derived from combined historic and Cassini imaging observations". The Astronomical Journal 132: 692. 
  2. IAUC 8432: Satellites and Rings of Saturn 2004 November 8 (claiming recovery of S/2004 S 3 on 17 October, 2004, in conflict with the later (2006) Spitale et al.)
  3. 3.0 3.1 Martinez, C; Ormrod, G; and Finn, H.; Cassini Discovers Ring and One, Possibly Two, Objects at Saturn JPL news release (September 9 2004)
  4. Based on above semimajor axis range, and Spitale et al. (2006)
  5. 5.0 5.1 IAUC 8401: S/2004 S 3, S/2004 S 4, and R/2004 S 1 2004 September 9 (discovery)

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