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IAUC 6764: Sats OF URANUS

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                                                  Circular No. 6764
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, 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)
URL http://cfa-www.harvard.edu/iau/cbat.html
Phone 617-495-7244/7440/7444 (for emergency use only)


SATELLITES OF URANUS
     B. J. Gladman, Canadian Institute for Theoretical Astrophysics;
P. D. Nicholson and J. A. Burns, Cornell University; and J. J. Kavelaars,
McMaster University, report the discovery of two probable distant
satellites of Uranus on CCD frames obtained with the COSMIC camera
on the Hale 5-m telescope at Palomar.  The objects were detected
by Gladman in early October on a set of twelve 360-s frames obtained
on Sept. 6 and 7.  The fainter object, S/1997 U 1, about 6' east of
Uranus, was estimated at R = 21.9.  The brighter object, S/1997 U 2,
about 7' west-northwest of Uranus, was at R = 20.4--but with B about 22
is fainter than the limit of the 1948 McDonald 2.1-m survey (Kuiper
1961, Planets and Satellites, p. 587); Uranus has hitherto differed from
the other giant planets in that it was not known to have any distant
satellites.  At the request of the Central Bureau, W. Offutt, Cloudcroft,
NM, began observing S/1997 U2 on Oct. 9.  Both satellites were reobserved
with the 5-m reflector in late October, although bad seeing permitted
detection of S/1997 U 1 on only one night, when it was found some 30"
from the prediction by Nicholson on the basis of a circular uranicentric
orbit.  D. J. Tholen (assisted by C. Herrick and R. J. Whiteley) observed both
satellites on Oct. 29 with the University of Hawaii's 2.2-m reflector.
Selected observations follow (for S/1997 U 1 and S/1997 U 2, respectively).

     1997 UT             R.A. (2000) Decl.       Observer
     Sept. 6.21723   20 31 52.90   -19 33 24.4   Gladman et al.
           7.20042   20 31 45.88   -19 33 52.2     "
     Oct. 27.14067   20 29 34.32   -19 42 44.7     "
          29.29708   20 29 39.85   -19 42 26.2   Tholen

     Sept. 6.22938   20 30 59.93   -19 30 51.9   Nicholson et al.
           7.20902   20 30 53.31   -19 31 13.3     "
     Oct.  9.15797   20 28 47.45   -19 37 32.8   Offutt
          18.10526   20 28 48.26   -19 37 14.7     "
          19.15664   20 28 49.43   -19 37 08.4     "
          20.11488   20 28 50.71   -19 37 02.3     "
          22.15709   20 28 54.07   -19 36 47.1     "
          26.14410   20 29 03.24   -19 36 08.2   Gladman et al.
          27.14091   20 29 06.04   -19 35 56.7   Offutt
          27.16834   20 29 06.15   -19 35 56.5   Nicholson et al.
          28.14304   20 29 09.11   -19 35 44.6     "
          29.28785   20 29 12.82   -19 35 29.4   Tholen
          31.10198   20 29 19.30   -19 35 04.0   Offutt

                      (C) Copyright 1997 CBAT
1997 October 31                (6764)              Brian G. Marsden

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