Central Bureau for Astronomical Telegrams
IAUC 3651: Sats OF SATURN; Poss. OPTICAL Id OF 1E 064301-1640.8
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Circular No. 3651
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 satellite or satellites
on images taken by the Voyager spacecraft on approach to Saturn In
1980 and 1981. The first, designated 1980 S 34, in a Voyager 1
image shuttered on 1980 Nov. 7.3615 UT at Saturn, is consistent with
an object moving in or near the orbit of Saturn III (Tethys) and
leading Tethys by 236o. The second, 1981 S 6, in a Voyager 2 image
taken on 1981 July 4.4944 at Saturn is consistent with an object in
or near Tethys' orbit and 99o ahead of Tethys. A search of other
Voyager 2 frames, assuming a range of orbital periods for the
object from 2 days down to that of Saturn II (Enceladus), resulted
only in negative observations. This leads to the suggestion that the
object or objects move in horseshoe orbits with respect to Tethys.
An estimate of 20 to 30 km is indicated for the object's diameter
in both observations. Orbital inclinations appear to be ~ 1o,
consistent with other objects moving in Tethys' orbit. If a single
object has been observed and has a motion of -0.576o/day with respect
to Tethys, it may be consistent with 1980 S 29, observed on 1980
Mar. 16 (cf. IAUC 3545, 3549), and will be observable near the
L4-point in early 1982."
POSSIBLE OPTICAL IDENTIFICATION OF 1E 064301-1640.8
W. A. Feibelman, Laboratory for Astronomy and Solar Physics,
Goddard Space Flight Center, communicates: "A 20-min exposure on
103a-O film obtained with the Thaw refractor at Allegheny Observatory
on 1964 Apr. 1 UT, using a technique to suppress the glare of
alpha CMa (-- Sirius), reveals a stellar image very close to the position
of the x-ray source ~ 2' southeast of Sirius, 1E 064301-1640.8
(cf. Chlebowski et al. 1981, Ap.J. 247, L35-38). The optical
candidate, of mpg ~ 13, is the only star visible within an area 2' x 2'
of the x-ray position (R.A. = 6h43m01s.9, Decl. = -16o40'51", equinox
1950.0) to a limit of mpg ~ 16. International Ultraviolet Explorer
observations are scheduled for the near future. Optical spectra
would be desirable, but are probably difficult to secure due to the
proximity of Sirius. The nearby dwarf nova and x-ray source
1E 0643.0-1648, ~9' south of Sirius, was photographed on 1960 Feb.
2 with the same equipment, when its brightness was near minimum at
mpg ~ 14."
1981 December 17 (3651) Daniel W. E. Green
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