Central Bureau for Astronomical Telegrams
IAUC 6034: 1993e
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Circular No. 6034
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)
T. Encrenaz, R. Schulz, J. A. Stuewe and G. Wiedemann report:
"We monitored Jupiter in the 3.0-3.5-micron range shortly after the
impact of fragment H using the IRSPEC imaging spectrometer on the
3.5-m New Technology Telescope at the European Southern Observatory. Our
observations (resolving power 1700) started on July 18.824 UT (13 min after
impact) at a rate of one spectrum per minute. Very strong emission was
detected over the whole spectral range from multiplets of the CH4 nu3 band
(J = 14 to J = 18). A spatial average over the impact region shows
that the signal intensity decreased exponentially with a
timescale of about 5 min. The IRSPEC spectrometer, its 4".4 slit
aligned along the parallel (latitude -44 deg) of the impacts, allows a
spatial analysis (spatial resolution 2".2) in this direction. At the
beginning of the sequence, the CH4 emission extended over about 10".
The slope of the spectrum shows drastic variations along the slit,
corresponding to a large range of rotational temperatures. In the
first image, the peak of intensity (at the center of the emission)
corresponds to a rotational temperature of about 700 K. On the leading
side, the intensity is much weaker, but its rotational temperature
reaches several thousand degrees. Both the hot and the central regions
cooled gradually to temperatures of about 1000 and 500 K, respectively,
15 min after the first image."
Reports received via the SL9 message center indicate that there
were no obvious detections of the impacts of fragments T = 4 (Calar
Alto Observatory, South African Astronomical Observatory), U = 3
(Palomar Observatory, Teide Observatory, Swedish Solar Telescope at
La Palma, University of Massachusetts Whately Observatory, McDonald
Observatory) or V = 2 (McDonald, Palomar, Steward Observatory,
Siding Spring Observatory).
The impact of fragment W = 1 was recorded by SPIREX (cf. IAUC 6026)
on July 22.343 UT, a preliminary estimate indicating that the site was
as bright as that of fragment E at 2.36 microns. CASPIR (cf. IAUC
6024) detected a slight brightening at 2.34 microns on July 22.337 that
faded briefly by 22.340, then strongly reappeared, saturating the detector
on 22.342 as the W site came into view; narrow-band imaging beginning on
22.345 showed strong emission at 4.78 microns. IRIS K-grism cubes
(cf. IAUC 6024) showed the W impact as a distinct, bright, pointlike
source slightly south of the K site on July 22.342; the W
feature brightened dramatically, saturating the detector on 22.344, when
it was at least 200 times brighter than the south polar hood and
about 4.5 times brighter than Ganymede at 2.34 microns.
A. C. Beresford, Myrtle Bank, South Australia, observed the W impact
site visually as it crossed Jupiter's central meridian on July 22.436 UT.
1994 July 22 (6034) Brian G. Marsden
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