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IAUC 3507: Sats OF JUPITER; SATURN; Notice

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                                                  Circular No. 3507
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM     Telephone 617-864-5758

     S. P. Synnott, Voyager Navigation Team, Jet Propulsion Laboratory,
informs us that the Voyager 1 observations reported on IAUC
3470 as confirmation of 1979 J 1 in fact refer to another satellite,
designated 1979 J 3.  Of diameter perhaps 40 km, 1979 J 3 has also
been detected in transit across Jupiter in at least half-a-dozen
Voyager 2 frames as well, and its revolution period is determined
as 7h04m30s +/- 3s.  1979 J 1, of diameter perhaps 25 km, has not been
identified in frames other than its discovery ones, and its
revolution period remains at 7h09m +/- 1m (Jewitt et al. 1979, Science 206,
951).  At the epoch of the Voyager 2 observations (1979 July) 1979
J 1 and 1979 J 3 were separated by about 160o in longitude.  Images
of the satellite 1979 J 2 have now been identified in both Voyager
1 and Voyager 2 data, and its revolution period has been refined to
16h11m21s.3 +/- 0s.5.

     J. Lecacheux and B. Fort, Observatoire de Meudon, report: "CCD
observations of the Saturnian E ring on Mar. 16-17 at Pic du Midi
lead to a radial structure unlike that proposed on IAUC 3497 by the
Space Telescope Wide Field/Planetary Camera Team.  In a paper
submitted to Icarus on July 10 we note a broad maximum (E1) in density
between 4.15 and 4.6 (+/- 0.2) Rs from Saturn; this is roughly midway
between Enceladus and Tethys.  There is a second, narrower component
(E2) near 5.7 Rs, somewhat inside the orbit of Dione.  Such a
two-component model is supported by quick-look electronographic
observations on Feb. 28-29 and Mar. 1.  We wish to point out the
difficulty of discriminating between stationary condensations that are
real components of the rings and transient ring knots due to
satellites (1980 S 6, perhaps also 1980 S 13) moving in Dione's orbit or
possibly due to similar unknown bodies orbiting at various
distances from Saturn's center."

     Contributors are reminded that the recommended way of contacting
the Central Bureau is by TWX/telex to the number 710-320-6842
(answerback ASTROGRAM CAM).  This number, followed perhaps by
for the address in messages sent by telegram or cablegram.

1980 August 26                 (3507)              Brian G. Marsden

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