Central Bureau for Astronomical Telegrams
IAUC 6024: 1993e
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Circular No. 6024
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM EASYLINK 62794505
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
PERIODIC COMET SHOEMAKER-LEVY 9 (1993e)
The Hubble Space Telescope Team reports a location for the feature
created by the impact of fragment A = 21. A streak ranges from
jovicentric latitude B = -42 +/- 1 deg, System III longitude L =
186 deg to B = -39 +/- 1 deg, L = 188 deg.
At 410 nm the maximum radial extent of the dark region
surrounding the streak is 12 000 km. Although the region appears
to be spatially circularly symmetric, the intensity distribution
appears to be asymmetric, being more apparent to the south.
A bright feature appears detached 1000-1500 km above the limb
on July 16.846 UT in the 953-nm filter, but it is not present in an
image 3-min earlier. A possible interpretation is
that the feature is visible by reflected sunlight and that the apparent
detachment is due to the shadow of Jupiter on the plume.
Numerous reports, most of them received via the SL9
message center, indicate no detection of the impact of fragment B = 20.
However, at the W. M. Keck Observatory, Mauna Kea, I. de Pater, J. Graham
and G. Jernigan clearly recorded a faint plume in L (3.27-3.44 microns)
at the expected position, starting on July 17.122 UT, fading around
17.134; and monitoring by S. Miller, M.-F. Jagod, T. Geballe and T.
Brooke of the H3+ ionospheric lines at 3.5 microns with the CGS4 echelle
spectrometer on UKIRT showed a fivefold brightening of the emission
around July 17.118, fading until 17.181.
The SL9 message center also relays that an impact associated with
fragment C = 19 was detected by P. McGregor and M. Allen at 2.34 microns
using the CASPIR infrared camera on the Australian National University
2.3-m telescope and by D. Crisp, V. Meadows, S. Lumsden and S. Lee using
IRIS on the 3.9-m Anglo-Australian Telescope at Siding Spring. The
event, seen at the limb on July 17.306 UT, brightened appreciably during
the first 5 min and was still visible after one hour. A weaker
event on July 17.267 has been identified by M. Brown as a probable
recurrence of impact A after one Jupiter rotation.
The NASA/IRTF Comet Collision Science Team reports that NSFCAM
2.248-micron observations beginning on July 17.285 UT did not record
any obvious flash on Io and Europa, but the data are yet to be
photometrically reduced. On July 17.302 both the remnant of
the A impact (with a surface brightness similar to that of the south
polar hood) and a dim spot from fragment C were detected. By July 17.304
site C was considerably brighter than site A, but by July 17.311 site C
had faded to about site A's brightness, and it continued to fade until
about July 17.319.
1994 July 17 (6024) Brian G. Marsden
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