Central Bureau for Astronomical Telegrams
IAUC 6515: Sats OF SATURN; C/1995 O1
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Circular No. 6515
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
Phone 617-495-7244/7440/7444 (for emergency use only)
SATELLITES OF SATURN
C. Roddier and F. Roddier, Institute for Astronomy (IfA), University
of Hawaii; A. Brahic, Observatoire de Paris; and J. E. Graves, M. J.
Northcott and T. Owen, IfA, report: "Images of Saturn's rings, taken in
Aug. 1995 with the University of Hawaii adaptive-optics system mounted on
the Canada-France-Hawaii telescope, have now been deconvolved and
carefully processed. They show evidence for at least nine additional
objects all orbiting in the F ring. A good orbital fit (including the
effects of the Saturnian J2 and J4 harmonics) was obtained for all of
them with a single distance of 140 500 +/- 500 km. The following list
includes the three objects already announced on IAUC 6407. As before,
the longitudes (uncertainty +/- 1 deg) are for the epoch 1995 Aug. 10.5
TT (at Saturn) and are measured from the ascending node of Saturn's
equator on the earth's J2000.0 equator: S/1995 S 11, longitude 302 deg,
estimated radius 12 km; S/1995 S 9, 317, 16; S/1995 S 12, 320, 10;
S/1995 S 7 = 1995 S 8, 325, 20; S/1995 S 13, 330, 12; S/1995 S 14, 46, 16;
S/1995 S 15, 105, 12; S/1995 S 16, 114, 10; S/1995 S 17, 116, 10;
S/1995 S 18, 118, 10; S/1995 S 19, 120, 10; S/1995 S 5 = 1995 S 10, 131, 20.
We also find some evidence for S/1995 S 11, S/1995 S 15, S/1995 S 16 and
S/1995 S 17 in the HST data (cf. IAUC 6243). S/1995 S 12 is part of the
possible S/1995 S 9 arc structure mentioned on IAUC 6407, now resolved
into two components; we no longer see evidence for arc structures. The 12
objects listed above cover a total longitude range of 135 deg. Assuming
that objects are uniformly distributed, one can estimate that the F ring
contains some 32 of them with radii larger than 10 km."
COMET C/1995 O1 (HALE-BOPP)
H. E. Matthews, National Research Council of Canada and Joint
Astronomy Centre; D. Jewitt, University of Hawaii; and W. M. Irvine,
University of Massachusetts, report the detection in C/1995 O1 of
HNC[4-3] at 362.6 GHz using the James Clerk Maxwell Telescope
on Dec. 1.0 UT. Measured within a 13".5 (29 000 km)-diameter beam, the
integrated line intensity was 0.23 +/- 0.03 Ta* K km/s. Using nearly
simultaneous observations of HCN[4-3], the HNC/HCN production ratio
is estimated as 0.07. This is similar to the value measured earlier
in C/1996 B2 (IAUC 6353). Since the two comets were observed at quite
different heliocentric distances (2.14 and 1.22 AU), the results
suggest that the observed HNC is a parent molecule present in the
nuclear ices and not a product of photochemistry in the coma. The
HNC/HCN ratio is consistent also with an origin for these species in
an interstellar cloud (cf. Irvine et al. 1996, Nature 383, 418).
(C) Copyright 1996 CBAT
1996 December 6 (6515) Brian G. Marsden
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