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THE ASTRONOMER Electronic Circular No 862      1994 July 20 19.47UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise,  Basingstoke,
Hants, RG22 4PP,England. Telephone/FAX(0256)471074 Int:+44256471074
INTERNET: GMH at AST.STAR.RL.AC.UK  or    GMH at GXVG.AST.CAM.AC.UK
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PERIODIC COMET SHOEMAKER-LEVY 9 (1993e)/COLLISION WITH JUPITER
Fragment G
N.James, Chelmsford, UK reports visual detection of a large dark
spot at the longitude of the impact of fragment G. It crossed the
Central Meridian on July 18 at about 20.00UT. The spot looked
initially like a shadow transit (although none were in progress)
and was visible even at x50 in a 0.075-m refractor. In the
0.30-m reflector x180 it occasionally showed fine structure under
good seeing.
Fragment H
Mark Kidger, Teide Observatory, reports:
"Around 19:26UT on 1994 July 18, Fragment H (14) impacted with
Jupiter. The Carlos Sanchez Telescope (1.52m infrared telescope)
and IAC-80 (an 82cm optical telescope) detected the explosion when
it reached the edge of the disc of the planet at 20:07UT. The mark
left by the explosion was almost as large as the Great Red Spot,
some 20 thousand kilometres in length. Unlike the impact of
Fragment A last Saturday, the explosion of Fragment H was
immediately visible through a filter tuned to the wavelength of
methane gas,  when it reached the edge of the disc. The impact zone
was immediately visible without having to process the images. The
brightness of the visible cloud was  clearly superior to that of
Fragment A, which is logical given that Fragment H was one of the
larger ones in the comet. The night offered a series of thrilling
views, such as that of the cloud from Fragment H on the edge of
the planet at the same time that the enormous cloud from Fragment
G was crossing the centre of the disc. Along with fragment Q,
which will impact on Wednesday night, Fragment G is the very
largest and has left a mark on the planet which is some 30
thousand kilometres long. This cloud is larger than the Great Red
Spot, which could be seen on the disc at the same time. Later, the
near simultaneous appearance of the twin spots from impacts
E and F left four impact clouds lined up across the face of the
planet at the same time."
James Lancashire, Cambridge, UK reports his visual observation
with the 0.20-m refractor at the University at Cambridge
Observatories of the central part of impact site H crossing
Jupiter's central meridian on July 18.926UT.
Fragment K
At Okayama Astrophysical Observatory an initial 2.36-micron flash
was detected on July 19.434, followed by an increase on
July 19.438 that reached a maximum around 19.443 of perhaps more
than 20 times the brightness of Io.  M. A'Hearn, University
of Maryland, reports that R filter observations at the Perth
Observatory during July 19.417-19.437 showed no hint of a flash
reflected from Europa, then in eclipse; beginning
July 19.441 methane 893-nm filter observations showed a definite
prominence above the apparent limb of Jupiter having
approximately the same surface brightness as other portions of
that latitude belt.
IAUC 6028

Guy M Hurst







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Date: Thu, 21 Jul 1994 17:37:29 +1000