Central Bureau for Astronomical Telegrams
IAUC 3656: Sats OF SATURN; Poss. COMET SHCHERBANOVSKIJ; 1981h
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Circular No. 3656
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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
SATELLITES OF SATURN
S. P. Synnott, Jet Propulsion Laboratory, reports: "I have
found two observations of an unidentified object or objects near
the L4 point of Saturn IV (Dione) in frames taken by the Voyager 2
spacecraft on its approach to Saturn. In a frame shuttered on 1981
Aug. 5.0222 UT at Saturn, there appeared an object, designated 1981
S 7, whose position was consistent with motion in Dione's orbit,
leading Dione by ~ 62o.0. A frame shuttered on 1981 Aug. 5.7349 UT
showed an object, designated 1981 S 8, whose position was also
consistent with motion in Dione's orbit, leading Dione by ~ 61o.0.
These objects were some 12o ahead of the known Dione Trojan, 1980
S 6 ('Dione B'), at the times of the observations. If the objects
are identical, the 1o.4/day motion toward Dione would indicate that
the satellite executes a horseshoe orbit with respect to Dione. It
seems unlikely that an object with such motion would happen to be
observed near a stability point unless there were many such objects.
This question will probably not be resolved by Voyager data alone.
I have also found a single observation of an unidentified object,
designated 1981 S 9, in a Voyager 2 frame shuttered on 1981 Aug.
8.3361 UT at Saturn. This object appears to move at an orbital
radius of 4.7 x 10**5 km, i.e., between the orbits of Dione and
Saturn V (Rhea), with a period of 3.8 days and a longitude of 162o
(measured from Saturn's vernal equinox) at the time of observation.
It is suggested that this object, which is estimated to be 15-20 km
in diameter, may be identical with the rather dubious object 1980
S 22, noted at 5-6 radii from Saturn (cf. IAUC 3474)."
POSSIBLE COMET SHCHERBANOVSKIJ
No further observations of this object (cf. IAUC 3655) have
been reported. Searches by E. Everhart at Chamberlin Observatory
on 1981 Dec. 30.4 UT and by R. E. McCrosky and colleagues at Oak
Ridge Observatory on Dec. 30.3 and 31.3 failed to reveal anything
brighter than m1 ~ 19 within ~ 0o.5 of the extrapolated position.
PERIODIC COMET KEARNS-KWEE (1981h)
G. M. Hurst, Wellingborough, England, communicates the following
total visual magnitude estimates and coma diameters by G. S.
Keitch, Wrington: 1981 Nov. 27.94 UT, 13.6, 0'.6; 29.05, 13.7, 0'.5;
Dec. 1.14, 13.6, 0'.7; 3.13, 13.6, 0'.7.
1982 January 8 (3656) Brian G. Marsden
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