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                                                  Circular No. 4168
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 617-495-7244/7440/7444

     B. A. Smith, on behalf of the Voyager Imaging Science Team,
reports the discovery of three more satellites of Uranus.  Revolution
periods  P  (in hr), orbital semimajor axes  a  (in km) and
estimated satellite diameters  D  (in km) are as follows:

  Object      P       a      D     Object      P       a      D

  1986 U7    7.92   49 300   20    1986 U9   10.38   59 100   50
  1986 U8    8.92   53 300   25

1986 U7 and U8 seem to be shepherding satellites for the N ring.
The diameters are based on a newly-measured albedo of ~ 0.05 for
1985 U1.  This albedo essentially doubles the estimated diameters
for the other seven new satellites (IAUC 4159, 4164 and 4165),
which thus become: 1985 U1, 150 km; 1986 U1, 50 km; 1986 U2, 40 km;
1986 U3, 40 km; 1986 U4, 30 km; 1986 U5, 30 km; 1986 U6, 30 km.
1986 U7 and U8 were found on Jan. 20, 1986 U9 on Jan. 23.  A new
ring, located at close to 50 000 km from the center of Uranus and
provisionally designated 1986 U1R, was detected on Jan. 24.

     The fifth edition of the 'Catalogue of Cometary Orbits', a
joint publication of the Central Bureau for Astronomical Telegrams
and Minor Planet Center, is now available.  The 102-page book,
which is in the same general form as the 1982 edition, contains
1187 sets of orbital elements calculated up to the end of 1985 Dec.
Subscribers to these Circulars may purchase the new edition for
$6.00 (half the cost to nonsubscribers), and arrangements can be
made to debit a subscription account accordingly.  The basic part
of the catalogue (including a direct reference to the comet names)
can also be purchased in the form of seven ASCII files on a
diskette; the diskette also contains (compiled) computer programs to
extract specific orbits from the catalogue and to generate ephemerides,
either from such orbits or from similar user-prepared data.
The diskette is being issued in IBM-PC DOS 2.0 double-sided,
double-density format (and it should be noted that the computer
programs require an 8087 mathematical coprocessor) for $100.00 or in
VAX/VMS format (either 8-inch or 5.25-inch, double density) for
$150.00.  A magnetic-tape version (without programs) costs $250.00.

1986 January 27                (4168)              Brian G. Marsden

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