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IAUC 7980: S/2001 U 1; S/2002 (121) 1

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IAUC number

                                                  Circular No. 7980
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)

S/2001 U 1
     A new candidate for a satellite of Uranus, of mag R =
25.3-25.5, was found by M. Holman, Harvard-Smithsonian Center for
Astrophysics (CfA); J. Kavelaars, now at Dominion Astrophysical
Observatory; and D. Milisavljevic, McMaster University, with the
4-m reflector at the Cerro Tololo Interamerican Observatory (CTIO)
on 2001 Aug. 13.  Kavelaars obtained confirmatory images with the
Canada-France-Hawaii Telescope on Aug. 25.  Following further
measurements by B. Gladman, from images obtained by P. Nicholson
and C. Dumas with the 5-m Hale reflector at Palomar on Sept. 21 and
by J.-M. Petit with the European Southern Observatory 8.2-m UT3
telescope at Paranal on Nov. 15, B. G. Marsden, CfA, provided a
prediction for the 2002 opposition that allowed Gladman to recover
a candidate for the object on Paranal images obtained by P.
Rousselot and O. Mousis on 2002 Sept. 5, after which Holman, with
the help of T. Grav, confirmed the recovery on CTIO 4-m reflector
images obtained on 2002 Aug. 13.   Marsden established definitively
an orbit with a = 0.057 AU, e = 0.21, i = 166 deg (to the ecliptic)
and that H = 12.8.  Full details of the astrometry and orbit
calculation, as well as a current ephemeris, are provided on MPEC

S/2002 (121) 1
     W. J. Merline, Southwest Research Institute (SwRI); P. M.
Tamblyn, Binary Astronomy and SwRI; C. Dumas, Jet Propulsion
Laboratory (JPL); L. M. Close, University of Arizona; C. R.
Chapman, SwRI;  F. Menard, Observatoire de Grenoble; W. M. Owen,
JPL; and D. C. Slater, SwRI; and J. Pepin, University of Colorado,
report the discovery on Sept. 28.6 UT of a satellite of (121)
Hermione (a C-type, Cybele-family asteroid of diameter 209 km) from
J-, H-, and K'-band direct imaging with the 10-m Keck II Telescope
(+ NIRC2/AO adaptive optics sysem) on Mauna Kea.  The satellite was
tracked until it became inaccessible to the telescope; over this
0.5-hr baseline, no relative motion was detected (a search for
known background/foreground small bodies with similar position and
velocity reveals no candidates closer than 1 deg that are of
similar brightness to the satellite).  On Sept. 28.6334, the
secondary was at 0".43 separation (projected separation 630 km) in
p.a. 257 deg.  The K brightness difference is about 6 mag, giving
an estimated diameter of the satellite of about 13 km.

                      (C) Copyright 2002 CBAT
2002 September 30              (7980)            Daniel W. E. Green

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