Central Bureau for Astronomical Telegrams
IAUC 6041: JUPITER AND 1993e
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Circular No. 6041
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)
JUPITER AND COMET 1993e
R. Prange and C. Emerich, Institut d'Astrophysique Spatiale,
Orsay; A. Talavera, International Ultraviolet Explorer (IUE)
Observatory, European Space Agency, Vilspa; W. Harris, G. Ballester, and
M. Combi, University of Michigan; T. Livengood, Goddard Space Flight
Center, NASA; and M. McGrath, Space Telescope Science Institute,
report: "Nearly continuous ultraviolet spectral observations of
Jupiter (range 115-330 nm, resolutions 0.014-0.6 nm) have been
performed with IUE during July 13-24. These had been preceded by
extensive observations in June, which provided a comprehensive,
two-dimensional baseline database (latitude/local time), to which
the impact and post-impact observations can be compared. Using the
3" small aperture, we have monitored the evolution of the ultraviolet
spectral features in the areas caused by impacts from comet
fragments A, B, E, G, K, Q, R, S, and W as they transited across
the Jovian disk. The observations have been repeated a few rotation
periods later, and monitoring of impact sites will continue until
Aug. 15. Many absorption and emission features have been seen.
Preliminary comparison of spectra from impact sites with those taken
under similar geometrical conditions before and after the impact of
nucleus A shows new, unidentified absorption lines at 176 and 178 nm
and emission lines near 182 and 330 nm. The first emission lines
could be tentatively attributed to S I lines at 180.8/182.0 nm, or
to a brightening of the pre-existing Si II triplet at 180.7/181.6/
181.7 nm. The second one might be due to a Na fluorescence line at
330.2 nm. The comparison also suggests a global brightening of the
impact region by 10-20 percent. Although small pointing errors
could simulate such an effect, it is consistent with the Hubble
Space Telescope WFPC2 images reported for impact A. The brightness
decreased to its normal level in < 2 hr, as the feature rotated
across the disk. The auroral emission at Lyman-alpha and in the H2
Werner and Lyman bands has generally been weak (especially the
northern aurora), possibly as a consequence of the passage of dust
through the Jovian magnetosphere. The Fine Error Sensor was used to
attempt detection of possible brightening of the Jovian satellites
from the flash of the direct impacts; Europa and Io were thus
observed for impacts A, H, L, and Q. No noticeable brightening at
the 1-percent level was found for impacts A and H."
1994 July 29 (6041) Daniel W. E. Green
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