[IAUC] IAUC 9060: JUPITER [25139-2009/08-R1]

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                                                  Circular No. 9060
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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JUPITER
     As noted on CBET 1882, J. H. Rogers, Jupiter Section Director,
British Astronomical Association, reported the discovery by Anthony
Wesley (Murrumbateman, NSW, Australia) on CCD images taken around
July 19.56 UT of a "virtually black" spot in Jupiter's South Polar
Region, very similar in appearance to the impact spots of comet
D/1993 F2 in July 1994.  Rogers adds that the spot is at longitude
216 deg (System II) and that T. Mishina (Japan) also reported the
spot in an image taken at about the same time.
     CBET 1882 also contains the report by F. Marchis and M. H.
Wong that analysis of observations of Jupiter's atmosphere
collected by P. Kalas, M. Fitzgerald, and J. Graham using the NIRC2
near-infrared camera at the W. M. Keck II telescope during July
20.468-20.474 UT (central meridian longitudes 283 deg-288 deg,
System III) revealed the presence of an anomalous bright feature
centered at planetographic coordinates 305 deg +/- 1.5 deg west, 57
deg +/- 1.5 deg south.  This feature is apparently the same as
Wesley's dark spot, interpreted to be an impact in the atmosphere
of Jupiter.  The scar, having an area of about 200 million square
km and well seen in the K_p filter centered at 2.124 microns, has a
complex shape, composed of an impact site with two prominent
features separated by about 2 deg and an ejecta field that extends
some 10 deg toward the west.  The scar is marginally detected in
observations recorded in H-band (centered at 1.633 microns) and in
CH_4 (centered at 1.681 microns) filters.  Further observations
during July 20.619-20.627 (central meridian longitudes 54-62 deg)
do not show evidence for additional impacts.
     F. Marchis, University of California at Berkeley and SETI
Institute; and R. Hueso Alonso, University of the Basque Country,
further report on a preliminary analysis of observations of
Jupiter's atmosphere collected by O. Mousis, Observatoire de
Besancon; G. Orton and L. Fletcher, Jet Propulsion Laboratory; and
S. Perez-Hoyos, University of the Basque Country, recorded with the
Very Large Telescope (Yepun) and its adaptive-optics system NACO
during July 26.311-26.370.  Images taken with the IB248 filter
(centered at 2.48 microns; width 0.06 microns) revealed that the
feature located between 295 deg and 315 deg west longitude (in
System III) and centered at 55 deg south latitude has a
significantly evolved shape by comparison with the Keck telescope
K_p (2.12 microns) data taken on July 20.468 (noted above).  Six
days after this observation, the two maxima are now barely
distinguishable, separated by 8 deg in latitude.  The brightest
peak is centered at 312 deg west.  The continued longitudinal
shearing is consistent with several amateur observations of the
site and with the behavior of the impact sites associated with the
impacts of D/1993 F2 in 1994.

                      (C) Copyright 2009 CBAT
2009 July 31                   (9060)            Daniel W. E. Green