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IAUC 8373: 2004dd; 2004de; RINGS OF URANUS

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IAUC number

                                                  Circular No. 8373
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)

     Further to IAUC 8372, J. Graham and W. Li report the LOSS
discovery of an apparent supernova (mag about 17.1) on an
unfiltered KAIT image taken on July 12.44 UT.  The new object was
confirmed on an earlier image taken on July 1.45 (mag about 17.0).
SN 2004dd is located at R.A. = 0h27m52s.98, Decl. = -1o48'46".3
(equinox 2000.0), which is 9".9 east and 9".5 south of the nucleus
of NGC 124.  A KAIT image taken on 2003 Dec. 28.25 showed nothing
at this position (limiting mag about 19.5).

SUPERNOVA 2004de IN NGC 3054
     L. A. G. Monard reports his discovery of an apparent supernova
on unfiltered CCD images taken on July 15.703 (at mag about 14.5
+/- 0.2) and 17.688 UT (mag about 14.6 +/- 0.1) with a 0.30-m
reflector near Pretoria, South Africa.  The new object is located
at R.A. = 9h54m27s.48, Decl. = -25o41'34".7 (equinox 2000.0), which
is 13" west and 37" north of the nucleus of NGC 3054.  Nothing is
visible at this position on images taken by Monard on June 20.7
(limiting red mag 17.7) or on his earlier images, and nothing is
visible on a red Digitized Sky Survey image (limiting mag 20).

     I. de Pater, University of California at Berkeley; H. B.
Hammel, Space Science Institute; and S. Gibbard, Lawrence Livermore
National Laboratory, report the detection of a faint sheet of
material in Uranus' ring system inside (and clearly displaced from)
rings 4, 5, and 6.  This sheet of material is visible between about
35000 and about 41000 km from the center of the planet, peaking in
intensity at 39000 km.  It must be the same ring as 1986 U 2R
(Stone and Miner 1986, Science 233, 39), discovered by Voyager in
1986 at visible wavelengths and large phase angles.  It is now for
the first time visible from the ground because the rings are slowly
'closing up', so that the line-of-sight traverses more ring
material.  The observations were conducted on 2004 July 3, 4, 8,
and 9 UT with the 10-m Keck II Telescope (+ NIRC2/AO) on Mauna Kea,
at K'-band (2.2 microns).  This sheet of material is visible in
single 2-5-min exposures; all data (about 1 hr) were combined to
derive the specifics given above.  The ring opening angle was about
11 degrees, with phase angle 2.25 degrees.  As we approach ring
plane crossing (in 2007), it is expected that more faint dust
sheets in the ring system will become visible.

                      (C) Copyright 2004 CBAT
2004 July 17                   (8373)            Daniel W. E. Green

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