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IAUC 3417: NEW RING AND Sats OF SATURN; 1979j; 1979i

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                                                  Circular No. 3417
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

     T. Gehrels and J. Van Allen, on behalf of other experimenters
and the Pioneer Project, communicate: "A new Saturnian ring,
provisionally named the F ring, was observed by the optical and
energetic-particle instruments on Pioneer 11 during the recent Saturn
flyby.  The ring has a width of ~ 2000 km and is centered on 2.35
Rs, where Rs, the approximate equatorial radius of Saturn, is
defined to be exactly 60 000 km.  An absorption feature in the
intensity of energetic particles was observed in the F ring for at least
one tens-of-kilometers-sized object.  The separation between the F
and A rings was provisionally named the Pioneer Division; its width
is ~ 2600 km.  The optical instrument (an imaging photopolarimeter)
observed a satellite, designated 1979 S 1, at ~ 2.53 Rs.  Independently,
three energetic-particle instruments observed an absorption
feature at 2.534 Rs, attributed to a nearby satellite, 1979 S 2, of
diameter ~ 170 km.  The positions in the orbit indicate that 1979
S 1 and 1979 S 2 are the same object; the orbital radius is similar
to that reported for 1966 S 2 (Fountain and Larson 1978, Icarus 36,
92; see also Aksnes and Franklin 1978, Icarus 36, 107)."

     This comet has been recovered by G. Schwartz and C.-Y. Shao
with the 1.5-m reflector at Harvard Observatory's Agassiz Station
as shown below.  The comet is diffuse and only weakly condensed.
The position is in very close agreement with the ephemerides on MPC
4670 and in Handb. B.A.A. for 1979.

     1979 UT          R. A. (1950) Decl.       m2
     Oct. 22.14946    1 44.6     - 1 39      ~20.5
          23.18314    1 43.8     - 1 45

     Total visual magnitude estimates: Sept. 27.04 UT, 12.1 (C. S.
Morris, Prospect Hill Observatory, 0.25-m f/7 reflector, 70 x); Oct.
9.03, 11.8, coma diameter ~ 2' (Morris); 15.02, 11.5 (A. Hale,
Annapolis, Maryland, 0.41-m reflector).

     Corrigendum: IAUC 3409, M. Hoffmann's observation.  R.A. should
read l3h23m17s.20; for 0.3-cm f/5 astrograph, read 0.3-m astrograph.

1979 October 25                (3417)              Brian G. Marsden

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