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IAUC 8209: S/2003 U 1, S/2003 U 2; P/2003 S2

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                                                  Circular No. 8209
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)
CBAT@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)


S/2003 U 1 AND S/2003 U 2
     M. R. Showalter, Stanford University; and J. J. Lissauer, Ames
Research Center, NASA, report the discovery of two previously
unknown inner satellites of Uranus in recent data from the High
Resolution Channel of the Hubble Space Telescope (HST) Advanced
Camera for Surveys.  A set of twenty-four 250-s clear-filter
(bandpass 300-900 nm) exposures was obtained during three
consecutive HST orbits between Aug. 25.8042 and 25.9659 UT.  Two
additional 120-s images were obtained during July 10.7273-10.7436,
and two 200-s images were obtained during Sept. 11.4765-11.5059.
S/2003 U 1 is visible on sixteen images from Aug. 25 and on all
images from July 10 and Sept. 11; its mean motion is 390.06 +/-
0.02 deg/day, corresponding to a semimajor axis of 97734 +/- 4 km,
and it appeared at maximum elongation off the northern ring ansa on
Aug. 25.97.  S/2003 U 2 is visible in six images obtained during
Aug. 25.8042-25.8297; it crossed the southern ansa on Aug. 25.823
at radial distance 74800 +/- 200 km, and its motion is consistent
with a circular orbit at this distance.  S/2003 U 1 is
approximately 5 percent as bright as Uranus XIV (Belinda), with a
signal-to-ratio (S/N) of 5-10 in most individual images, while
S/2003 U 2 is approximately 3 percent as bright as Uranus XIV, with
S/N = 4 in individual images.


COMET P/2003 S2 (NEAT)
     Further to IAUC 8208, M. Hicks reports the NEAT discovery of
another comet on images obtained at Haleakala (discovery
observation below), noting a coma diameter of 5" and a 15" tail in
p.a. 255 deg.  Following posting on the NEO Confirmation Page,
numerous observers have reported cometary activity from CCD images
obtained on Sept. 24.9-25.0 UT, including R. Apitzsch (Wildberg,
Germany; 2" coma), P. Birtwhistle (not 'Birthwhistle', as given on
IAUC 8208; 8" coma with a broad tail at least 20" long in p.a. 250
deg and a thin tail 20" long in p.a. 330 deg), F. Hormuth
(Heppenheim, Germany; 40" tail in p.a. 260 deg), and S. Gajdos and
A. Galad (Modra, Slovakia; coma diameter about 15" and tail
extending in p.a. 255-260 deg).  The available astrometry
(including prediscovery LINEAR observations from Sept. 19.4),
preliminary orbital elements (T = 2003 July 10.0 TT, Peri. = 259.6
deg, Node = 91.5 deg, i = 7.3 deg, equinox 2000.0, q = 2.294 UT, e
= 0.454, P = 8.6 yr), and an ephemeris appear on MPEC 2003-S65.

     2003 UT             R.A. (2000) Decl.       Mag.
     Sept.24.60807    2 00 41.55   - 0 03 43.4   18.0

                      (C) Copyright 2003 CBAT
2003 September 25              (8209)            Daniel W. E. Green

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