Central Bureau for Astronomical Telegrams
IAUC 6033: 1993e
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Circular No. 6033
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)
N. Walton, R. Catchpole, P. Rudd and A. Fitzsimmons, using the
Royal Observatories' Isaac Newton Telescope at Roque de los
Muchachos Observatory, report seeing the Na D lines in
emission at the time of impact L. The emission first appeared
on July 19.937 UT, reached maximum brightness on 19.938 and
had vanished by 19.944. Other faint, as yet unidentified emission
lines were also seen at the same time.
For the Hubble Space Telescope (HST) team, K. S. Noll, Space
Telescope Science Institute, reports the following result: "We have
identified CS2 in spectra of impact site G obtained with the HST
Faint Object Spectrograph. At least 13 separate bands from 187.3
to 206.4 nm are clearly observed. In the same spectra we have
previously positively identified S2 and enhanced NH3, and we have tentative
evidence for H2S (cf. IAUC 6031). CS2 is an expected product of
shock and/or solar extreme-ultraviolet induced chemical reactions
between H2S and CH4. We have also searched for bands of SO and SO2,
but no band from either molecule has been observed. The two spectra
were obtained on July 19.447 and 19.462 UT, more than three hours after
the impact of fragment G. The 0".9 aperture was positioned
at the center of the impact site."
The South African Astronomical Observatory reports via the SL9
message center that J. Shykula used the 1.9-m telescope for high-speed
K-band photometry of the impact of fragment S = 5. Definite brightening
began around July 21.640 UT, with peak brightness around 21.645 and
a return to relatively constant signal levels by 21.651; peak brightness
was nearly twice that seen for impact Q, with a peak K mag about 1.19.
Using the 0.75-m telescope and PtSi camera K. Sekiguchi obtained images
of Jupiter at 30-s intervals during the impact. A low-level brightening
began around July 21.636 and began to fade before a much more dramatic
brightening began around 21.640. Peak brightness occurred around 21.645,
and by 21.653 there was definitely no remaining obvious excess
brightness from this impact. The bright spot at the impact site could not
easily be separated from those for impacts R, G and D. The S impact plume
was considerably brighter than that seen for fragment H.
Observations with the MAGIC camera on the 3.5-m telescope
at Calar Alto were affected by an electronic problem until very shortly
before the S impact plume was detected at 2.3 microns on July 21.645 UT.
It became brighter than the nearby spots of previous impacts within about
2 min. It started fading on July 21.648 and eventually reached the level
of the other bright spots.
1994 July 21 (6033) Brian G. Marsden
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