Three New Outer Satellites of Saturn

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Three New Outer Satellites of Saturn Discovered

                                                  Circular No. 8836
Central Bureau for Astronomical Telegrams

S/2007 S 1, S/2007 S 2, AND S/2007 S 3
     Further to IAUC 8727, S. S. Sheppard, D. C. Jewitt, and J.
Kleyna have reported the discovery of three new satellites of
Saturn in data obtained earlier this year with the Subaru 8.2-m
reflector at Mauna Kea, aided by B. G. Marsden's ongoing linkages
and search ephemerides.  The astrometry and orbital data appear on
MPECs 2007-G38 and 2007-J09, showing orbital periods of 895, 793,
and 992 days for S/2007 S 1, S/2007 S 2, and S/2007 S 3,
respectively; the latter two objects have retrograde orbits.

                      (C) Copyright 2007 CBAT
2007 May 11                    (8836)            Daniel W. E. Green

One New Inner Satellite of Saturn find by the Cassini Spacecraft

                                                  Circular No. 8857
Central Bureau for Astronomical Telegrams

S/2007 S 4
     C. C. Porco, CICLOPS, Space Science Institute, Boulder; and
the Cassini Imaging Science Team report the discovery of S/2007 S 4,
a satellite orbiting in the region between Saturn XXXII (Methone)
and Saturn XXXIII (Pallene).  The satellite was first discovered in
a series of fifteen pairs of Cassini wide-angle camera images with
exposure times of 10 and 15 s, taken through the clear filter on
2007 May 30, spanning 6 hr.  Following a preliminary orbit fit, an
exhaustive search of other Cassini images generated a number of
additional detections.  The current observation arc, comprising 47
detections, spans 3.03 years between June 2004 and June 2007.
Numerical integration of the equations of motion shows that the
object is being influenced by a 10:11 mean-motion resonance with
Mimas.  A precessing-ellipse model fitted to the integrated orbit
for S/2007 S 4 over the month of May 2007 yields a = 197700 km, e =
0.001, i = 0.1 deg, and P = 1.03650 days.  S/2007 S 4 is located
approximately 3400 km beyond Saturn XXXII, but still interior to
the orbit of Saturn XXXIII, suggesting that the three may be part
of a larger group of satellites in this region.  Saturn XXXIII was
also observed in some of the S/2007 S 4 discovery frames.  If
S/2007 S 4 has the same disk-integrated reflectivity as Saturn
XXXIII, preliminary estimates suggest a physical radius for S/2007
S 4 of about 1 km.

                      (C) Copyright 2007 CBAT
2007 July 18                   (8857)            Daniel W. E. Green


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