%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% \documentstyle[12pt]{article} \topmargin 0in \oddsidemargin 0in \evensidemargin 0in \textheight 21.5cm \textwidth 15.5cm \parskip 8pt plus 3pt minus 2pt \parindent 0in \pagenumbering{arabic} \marginparwidth 0.4in \newcommand{\vs}{\vspace*{5 mm}} \newcommand{\bc}{\begin{center}} \newcommand{\ec}{\end{center}} \newcommand{\bi}{\begin{it}} \newcommand{\ei}{\end{it}} \newcommand{\np}{\newpage} \newcommand{\etal}{{\it et al.\/}} \newcommand{\hst}{{\it HST\/}} \newcommand{\ie}{i.e.,} \newcommand{\eg}{e.g.,} \newcommand{\magplus}{Mg$^{+}$} \newcommand{\kms}{km~s$^{-1}$} \newcommand{\qmgp}{\mbox{Q$_{\rm Mg^+}$}} \def\Mgone{Mg\,{\sc i}} \def\Mgtwo{Mg\,{\sc ii}} \def\Catwo{Ca\,{\sc ii}} \def\degr{\ifmmode ^\circ\else $^\circ$\fi} \font\mdt=cmr12 \font\bdt=cmbx12 \font\sdt=cmr12 \def \szero{S$_{0}$} \def \logs{log$_{10}$S} \def \cmt{cm$^{2}$} \def \chfour{CH$_{4}$} \def \ny{N'(y)} \def \no{N$_{0}$} \def \cotwo{CO$_{2}$} \def \htwo{H$_{2}$} \def \knuz{k($\nu$,z)} \def \dnu{$\Delta\nu$} \def \um{$\mu$m} \def \ubar{$\mu$bar} \def \nui{$\nu_{i}$} \def \nuthree{$\nu_{3}$} \def \no{N$_{0}$} \def \etal{et al.} \def \ie{i.e.} \def \pmd{$\pm$} \def\mic{$\mu$m} %\comment{HST SL9 summary paper} \def\refhstslscisum{ {Hammel, H.\ B., R.\ F.\ Beebe, A.\ P.\ Ingersoll, G.\ S.\ Orton, J.\ R.\ Mills, A.\ A.\ Simon, P.\ Chodas, J.\ T.\ Clarke, E.\ De Jong, T.\ E.\ Dowling, J.\ Harrington, L.\ F.\ Huber, E.\ Karkoschka, C.\ M.\ Santori, A.\ Toigo, D.\ Yeomans, R.\ A.\ West} {1995} {HST Imaging of Atmospheric Phenomena Created by the Impact of Comet Shoemaker-Levy 9} {Science} {{267}{1288}{1296}} {Hammel \etal} {} {} {H.\ B.\ Hammel \etal}} %\comment{Comet Shoemaker-Levy 9 impact prediction paper} \def\refjhcslprednat{ {Harrington, J., R.\ P.\ LeBeau, K.\ A.\ Backes, and T.\ E.\ Dowling} {1994} {Dynamic response of Jupiter's atmosphere to the impact of comet Shoemaker-Levy 9} {Nature} {{368}{525}{527}} {Harrington \etal} {} {} {J.\ Harrington \etal}} %\comment{Andy's linear wave model} \def\refikdcslgrl{ {Ingersoll, A.\ P., H.\ Kanamori, and T.\ E.\ Dowling} {1994} {Atmospheric gravity waves from the impact of comet P/Shoemaker-Levy 9 with Jupiter} {Geophys.\ Res.\ Lett.} {{21}{1083}{1086}} {Ingersoll \etal} {} {} {A.\ P.\ Ingersoll \etal}} \begin{document} \begin{center} {\bf Evolution of the SL9 Impact Sites and Numerical Experiments\\ with a Two-Layer Rigid-Lid Model}\\[6pt] \begin{it} Tadashi Asada \\ Kyushu International University \\[6pt] Isao Miyazaki \\ Oriental Astronomical Association \\[6pt] Tokuhide Akabane \\ Hida Observatory\\[6pt] \end{it} \end{center} Ground-based imaging of impact sites of Comet Shoemaker-Levy 9 on Jupiter was carried out in visible and near infrared wavelength. Many impact sites were found to be elongated in east-west direction due to the shear of the zonal flow. Numerical experiments with two-layer rigid-lid model indicate that an eddy evoluves to be elongated in east-west direction by the horizontal shear of the zonal flow in the case of small Rossby deformation radius, whereas it survives keeping its circular shape in the large deformation radius case. The evolution of impact sites seems to resemble the behavior of the eddy of small defomation radius. \newpage \bc {\bf IR-Images of Calar Alto: Investigation of the temporal development of the SL9 impact sites on Jupiter}\\[6pt] \bi Johannes Babion (University Observatory, Munich)\\ Hermann Boehnhardt (University Observatory, Munich)\\ Fionn Murtagh (ST-ECF ESO, Garching)\\ Jean L. Starck (CEA, DSM/DAPNIA, CE-SACLAY, 91191 Gif-sur-Yvette Cedex)\\[6pt] \ei \ec The SL9 impacts at Jupiter were imaged from Calar Alto (Spain) with the 3.5 m telescope + MAGIC Camera in the near infrared and with the 1.2 m telescope + CCD in the visual wavelength range. After the basic data reduction suitable deconvolution techniques (Babion et al, European SL9/Jupiter Workshop Proceedings, 1995) are applied to the images to sharpen the surface structures of the impact regions on the planet. Using our time series of multi-wavelength observations the temporal development of the SL9-impact is assessed. This still ongoing analysis adresses the rapid expansion during the initial phase after impact and the long-term diffusion of the ejecta structures on Jupiter. In this paper a report on the present status of the project is given and preliminary results are described. \np \begin{center} {\large \bf Dynamical Evolution of Comet P/Shoemaker--Levy\,9} \vspace{5pt} M.E. Bailey$^\ast$, V.V. Emel'yanenko$^\ast$ \& J.V. Scotti$^{\ast\dagger}$ \vspace{5pt} $^\ast$School of Computing and Mathematical Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF, England.\\ $^\dagger$Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona 85721, USA\\ \end{center} \vspace{1cm} We report on both the analytical and numerical investigation of the dynamical evolution of P/Shoemaker-Levy\,9. Secular perturbations on objects in temporary-satellite-capture (TSC) orbits about Jupiter cause frequent evolution on to orbits that allow tidal disruption or collision with the planet. The effect is analogous to the Sun-grazing phenomenon amongst high-inclination Halley-type orbits about the Sun, and it produces a much higher Jupiter-collision rate than that expected from a random encounter model. The order of magnitude of the collision rate is the probability ($\sim\! 10^{-1}$) for a long-lived TSC object to evolve into a Jupiter-grazing or Jupiter-colliding end-state by secular perturbations, multiplied by the rate of production of such TSC events per observable Jupiter-family comet per year ($\sim \! 2\times 10^{-4}$). Secular theory and direct numerical integrations show that the fragments of P/Shoemaker-Levy\,9 passed through a previous extremely close encounter with Jupiter in 1970, suggesting that the progenitor must also have made a close approach to Jupiter around this time. We discuss the similarity between this dynamical evolution and that found for variational orbits based on P/Gehrels\,3 and P/Helin-Roman-Crocket. Remarkably, P/Gehrels\,3 was also within the Roche radius of Jupiter at the same time as P/Shoemaker-Levy\,9 in 1970. Backward integrations of test particles with initial orbits similar to those of the P/Shoemaker-Levy\,9 fragments are used to investigate the distribution of possible source orbits for the progenitor of P/Shoemaker-Levy\,9. \np \bc {\bf Far-ultraviolet emissions from the impact sites of comet \mbox{P/Shoemaker-Levy 9}\\ with Jupiter}\\[6pt] \bi G.E. Ballester(1), W.M. Harris(1), G.R. Gladstone(2), J.T. Clarke(1),\\ R. Prange(3), C. Emerich(3), A. Talavera(4), S.A. Budzien(5),\\ P.D. Feldman(6), M.R. Combi(1), T.A. Livengood(7), M.B. Vincent(1),\\ M.A. McGrath(8), D.T. Hall(6), D.F. Strobel(6), J.M. Ajello(9),\\ L. ben Jaffel(10), D. Rego(1), G.F. Fireman(11), K.L. Jessup(1),\\ L. Woodney(12), S. Miller(13), and X. Liu(9)\\[6pt] \ei \ec \bi (1) U. of Michigan, (2) Southwest Res. Inst.,\\ (3) Inst. d'Astrophysique Spatiale, France, (4) IUE-VILSPA, Spain\\ (5) Naval Res. Lab., (6) Johns Hopkins U., (7) Goddard Space Flight Center\\ (8) STScI, (9) Jet Propulsion Lab.\\ (10) Inst. d'Astrophysique de Paris, France, (11) Computer Sciences Corp.\\ (12) U. of Maryland, (13) U. College London, UK\\[6pt] \ei Observations with the International Ultraviolet Explorer (IUE) during the collisions of fragments of comet P/Shoemaker-Levy 9 with Jupiter show far-ultraviolet emissions from the impact sites within a ~20 minute period centered around impact time. Positive detections of H2 Lyman- and Werner-band (1230-1620 A), H-Ly a, C 1657 A, and possibly Al+ 1671 A emissions were made for the K and S fragment impacts. Energies of at least 10(21) ergs were emitted at these wavelengths, corresponding to brightnesses of at least a few hundred kilo-Rayleighs. No thermal far-UV continuum was detected. The H2 spectrum is consistent with electron collisional excitation if significant CH4 absorption is included. Such emissions could result from magnetospheric and/or ionospheric plasma processes generated by the energetic impacts, and possibly related to the far-UV emissions imaged 40-50 minutes after the K impact with HST. In this emission process, the hydrogen could be atmospheric while the C and Al+ would have to be of cometary origin, and the CH4 absorption could be easily explained by a stratospheric column in the line-of-sight. Another type of emission process involves resonant and fluorescent scattering of continuum thermal radiation by upper atmospheric hydrogen and ablated comet material. The hot thermal far-UV radiation could have been produced by either the later stage of the fragment entry, when reaching sufficiently high pressure levels where the shock may have reached very high temperatures, and/or also by the early fireball which may have reached temperatures above ~3500 K when at low altitudes and behind the limb (cooling to below ~1800 K when directly observable from Earth). Only small quantities of cometary C and the possible Al+ would be needed for this emission process. The plausibility of this process depends on the shape of the H2 spectrum, which has not been modeled. Scattering of sunlight by the rising plume cannot explain the emissions, except possibly for the Al+ emission, and direct collisional excitation in the earliest entry stage or non-thermal emission by the early non-equilibrium entry shock could in principle have contributed to the emissions. \newpage \bc \vspace*{-1cm} {\bf 2$\mu$m spectro-photometry of Jovian aerosol clouds -- scattering opacities, vertical distributions and wind velocities}\\[6pt] \bi D. Banfield, P. Gierasch, S. Squyres, \& P. Nicholson (Cornell)\\ B. Conrath (Goddard), and K. Matthews (Caltech)\\[6pt] \ei \ec Spectro-photometric observations of Jupiter at 9 wavelengths in the 2.0 -- 2.35 micron band were taken on the 5m Hale telescope at Palomar during the 2 months following the impact of comet P/Shoemaker-Levy 9. From these, spectra of the discernable spots were measured as they evolved through this time. Spectra of 4 regions (South Polar Region, North Equatorial Zone, South Equatorial Zone and Great Red Spot) unaffected by the comet impacts were also measured. % A technique with which near-infrared reflection spectra can be inverted to yield vertical profiles of scatterer density is presented. For the wavelengths and bandwidths measured in this study, the sensitivity of the inversions extends from near 1 bar up to about 15mbar. This technique was used to estimate the height and total scattering opacity of the measured comet impact clouds, with the result that all comet impact clouds were found to lie near or above the vertical limit of our sensitivity, 15mbar. The lower limit of the clouds is around 50mbar. % The total scattering opacity of all of the clouds is seen to decrease by a factor near 1.7 over the 35 days spanned by the observations. This is consistent with a change in the mean particle size, with a general fall-out of some of the cloud material, and with a horizontal dispersion of clouds. West {\it et al.} (1995) suggest that the mean particle radius does increase over this time. We have not measured the horizontal dispersion of the clouds over this time period, and thus cannot yet separate out the three possible effects to examine particle fall-out rates. % The speeds of stratospheric winds experienced by these clouds were also measured by two different techniques. The first assumed an {\it a priori} latitudinal profile for the stratospheric winds (the tropospheric winds of Limaye (1986)) which was then scaled down. The scaling factors were chosen to deform early images of the clouds so that they best matched later images of the same clouds. The second technique imposed no {\it a priori} assumptions on the wind field, but rather measured it via a technique similar to that used in Limaye(1986). Early and later images were correlated with each other as a function of longitudinal shift for each latitude, yielding zonal velocities given by the shift of maximum correlation. Both techniques indicate wind speeds of order -5--15m/s ($\sim 1/2$ those measured by Voyager in this region). % The spectra of the unaffected regions of Jupiter are a very useful by-product of this data set. They can be used to verify calibrations, as well as to quantify the vertical distribution of aerosols in undisturbed regions. For the South Polar Region, we find a distribution of aerosols (total scattering optical depth $\sim 0.05$) peaking at about 25mbar, and extending down to near 100mbar. We are not sensitive to its top limit. The North and South Equatorial Zones show what appears to be a diffuse aerosol cloud (total scattering optical depth $\sim 2\times10^{-3}$) near or above the vertical limit of our sensitivity, overlying a perhaps higher tropopausal cloud deck at around 450mbar. The South Equatorial Zone shows more variability than the North. The Great Red Spot shows only a tropopausal cloud which is again slightly elevated compared to the rest of the planet, peaking at about 400mbar. Our reflectance spectra inversion technique can also be applied to other regions of the planet to investigate the distribution of aerosols there as well. \np \bc {\bf On the Orbital Evolution and Origin of Comet Shoemaker-Levy 9}\\[6pt] \bi L.A.M. Benner and William B. McKinnon\\ Dept. Earth and Planetary Sci. and McDonnell Center for the Space Sci.\\ Washington University\\ Saint Louis, MO 63130\\ (e-mail: mckinnon@wunder.wustl.edu)\\[6pt] \ei \ec Based on our dynamical study (submitted for publication), we find that Shoemaker-Levy 9 (SL-9) orbited Jupiter for most of this century, and possibly longer, by far the longest known temporary capture by Jupiter. Secular solar perturbations caused SL-9's inclined and distant jovicentric orbit to alternate, with a period of $\sim$25 yr, between intervals of nearly polar inclination (i $\sim 90^{\circ}$) and low eccentricity and intervals of lower inclination (either prograde or retrograde) and nearly parabolic eccentricity (e $\approx$ 1.0). This latter phase brought the comet close enough for disruption on 8 July 1992 and collision in July 1994. Immediately prior to the 1992 perijove, the comet passed through Jupiter's tenuous inner ring halo at $1.62 \pm 0.01$ jovian radii, but the population of macroscopic bodies in this portion of the ring is probably insufficient for collisions to have weakened the nucleus or disrupted the nucleus. The comet's trajectory was among the most chaotic of any known solar system body, with an effective Lyapunov time in jovian orbit of $\sim$10 years. Because of the shortness of the Lyapunov time compared to the probable length of temporary capture about Jupiter, SL-9's heliocentric orbit prior to capture can only be discussed in a statistical sense. The ensemble of possible pre-capture solutions describe low e and i orbits just exterior and interior to that of Jupiter. These orbits are indistinguishable from those of "quasi-Hilda-type" Jupiter-family comets, a group known to strongly interact with Jupiter and experience extended temporary satellite captures. Based on their Tisserand parameters, the orbits are not consistent with a recently escaped Trojan asteroid, but an origin as such is not impossible. \np \begin{center} {\bf Mid--IR High--resolution Spectroscopy of the SL9 Impact Sites: Temperature and HCN Retrievals}\\[6pt] \begin{it} B.\ B\'ezard (Paris-Meudon Obs.), C.A.\ Griffith (N.~Arizona U.), D.\ Kelly (U.~Texas), J.\ Lacy (U.~Texas), T.\ Greathouse (N.~Arizona U.), and G.\ Orton (NASA/JPL)\\[6pt] \end{it} \end{center} We present observations of the SL9 comet's crash that were taken at the NASA Infrared Telescope Facility (Mauna Kea, Hawaii), with the U.\ Texas mid--infrared echelle spectrometer IRSHELL. Various impact sites were imaged at a spatial resolution of 1.5 arcsec and a resolving power of about 15000. Several spectral intervals in the 10--$\mu$m window were observed. CH$_4$ lines around 1234 cm$^{-1}$ and a C$_2$H$_2$ line near 743 cm$^{-1}$ were observed on July 20, 30 and 31 to monitor stratospheric temperatures and constrain the analysis of the observed NH$_3$ emission lines (see poster by Griffith {\it et al.\/}). CH$_4$ line spectra recorded 23 hrs after impact K and 11 hrs after impact L show enhanced emission over these sites. This enhancement is very pronounced for the 1233.455--cm$^{-1}$ line but negligible for the $\sim$100 times weaker lines at 1233.147 and 1234.226 cm$^{-1}$, implying that the stratospheric warming was confined to levels above $\sim$0.2 mbar. We derive temperature enhancements around 45~K for the L impact and 25~K for the K impact at 1~$\mu$bar at the time of the observations. Mapping of the C$_2$H$_2$ line at 743.265 cm$^{-1}$ indicates a local warming of $\sim$10~K in the 10--$\mu$bar region over the E site, 2.6 days after impact. HCN emission was detected at 744.458 cm$^{-1}$ over all impact sites observed. The retrieved HCN column density is somewhat sensitive to assumptions in the gas vertical distribution and in the temperature profile. A preliminary analysis indicates a column density of about 10$^{16}$ molec cm$^{-2}$ at the center of the E site 2.6 hrs after impact, 3 times larger than inferred from millimeter observations of impact G (Marten {\it et al.\/} 1995). \newpage \bc {\bf Detection of Water in the "Splash" of Fragments G and K of Comet \mbox{Shoemaker-Levy 9}}\\[6pt] \bi G. L. Bjoraker\\ NASA/GSFC\\[6pt] T. Herter, G. Gull, S. Stolovy, and B. Pirger\\ Cornell University\\[6pt] \ei \ec We observed Jupiter on 17-19 July 1994 using the Kuiper Airborne Observatory (KAO) deployed out of Melbourne, Australia. The KAO Echelle Grating Spectrometer uses a Si:As BIB array with 128 spectral elements at a resolving power of 9000 and 10 spatial elements on Jupiter. We detected H2O emission lines at 7.7, 22.6, and 23.9 microns. We have obtained temperatures at the peak of the splash phase for the G and K fragments, for the 3 microbar pressure level. The H2O lines at 7.7 microns were visible for 10 minutes; those at 23.9 microns were visible for about an hour in G. We have also obtained column abundances for H2O for both G and K using 7.7 micron data. Our estimate should be considered a lower limit to H2O as the 7.7 micron data are sensitive only to the portion of water at the highest temperatures. The G and K fragments exhibited remarkably similar spectra at the peak of the splash at 7.7 microns. The column abundance of "hot" H2O at the peak of the splash was roughly comparable to that of CH4. We interpret the CH4 emission as due to pre-existing jovian CH4 heated by infalling ejecta. We believe that the oxygen in the observed H2O is derived from cometary material, although we cannot distinguish between H2O that may have been formed through shock chemistry from H2O that may have survived the initial explosion. A combination of Galileo/NIMS, KAO/HIFOGS, and KAO/KEGS data favor a scenario in which the fragments did not reach the water cloud in order to excavate jovian H2O. \np \begin{center} {\bf EFFELSBERG OBSERVATIONS OF JUPITER'S RADIO BRIGHTNESS VARIATIONS INDUCED BY COMET SHOEMAKER-LEVY 9} \\[6pt] \bi M.K. Bird \& \underline{O. Funke}\\ Radioastronomisches Institut\\ Univiversit\"at Bonn\\ Auf dem H\"ugel 71, 53121 Bonn, Germany\\[6pt] J. Neidh\"ofer\\ Max-Planck-Institut f\"ur Radioastronomie\\ Auf dem H\"ugel 69, 53121 Bonn, Germany)\\[6pt] I. de Pater\\ Dept.\ of Astronomy\\ University of California\\ Berkeley, CA 91109, U.S.A.\\[6pt] \ei \end{center} As part of a worldwide campaign of Jovian radio observations associated with the impact of comet SL9, measurements of Jupiter's flux density and polarization were recorded for three wavelengths ($\lambda$ = 2.8, 6, 11 cm) at the Effelsberg 100-m Radio Telescope of the Max-Planck-Institut f\"ur Radioastronomie. The nonthermal flux densities, attributed to gyrosynchrotron radiation from energetic electrons in the Jovian radiation belts, are normalized to 4.04 AU and corrected for the finite size of the emitting region with respect to the beamwidth, an effect which can be quite important at the higher frequencies. Two parameter fits were made for each observation day to the Jovian beaming curve, the radio flux density as a function of Jupier's rotational phase. The value of the constant term, the flux density $S_0$, increased from 4.4 Jy to 5.7 Jy (27\%) at $\lambda$ = 11 cm and from 2.4 Jy to 3.9 Jy (62\%) at $\lambda$ = 6 cm during the impact week from July 16 to July 22. No changes in the radio brightness of 25.6 $\pm$ 0.8 Jy could be detected at $\lambda$ = 2.8 cm. The brightness level did not rise uniformly, but was pushed up preferentially at specific System III longitudes. Most recent observations in February 1995, more than six months after the the SL9 collision, indicate that Jupiter's nonthermal radiation has still not returned to its pre-impact level. \np \bc {\large\bf{Europe and Io photometry during SL9 fragments impacts}}\\[6pt] \bi C. Blanco$^{1}$, G. Leto$^{1,2}$, D. Riccioli$^{1}$\\[6pt] \ei \ec \bi $^{1}$ Astronomy Institute of Catania University\\ Viale A.Doria 6, I 95125 Catania, Italy\\[6pt] $^{2}$ Institute of Radioastronomy, VLBI Station\\ C.P. 169, I-96017 Noto (SR), Italy \\[6pt] \ei We report on the photometric monitoring of Europa and Io during the impacts of the comet P/Shoemaker-Levy 9 fragments on Jupiter. BV photoelectric observations were collected at the Serra La Nave (SLN) Station of Catania Astrophysical Observatory. High speed photometry at 0.1~sec and 1~sec integration time was performed by using the 91-cm Cassegrain telescope equipped with a photon counting photometer provided by a cooled photomultiplier. Constraints due to SLN geographical position have limited our observations to 3 impact events (A, H, Q family). For A and Q events we have recorded, for Europa and Io respectively, light brightning exceeding two sigma. The times of the events, their duration and the energy budget are given and discussed in the light of other observer results. \np \bc {\bf Radiation study of two very bright terrestrial bolides}\\[6pt] \begin{it} J. Borovi\v cka and P. Spurn\'y \\ Astronomical Institute, 251 65 Ond\v rejov Observatory, Czech Republic \\[6pt] \end{it} \end{center} For the comparison with the entry phase of the SL-9 collision with Jupiter, light curves and spectra of two of the brightest photographed bolides were studied. The \v Sumava bolide (EN\,041274) reached $-21$ absolute (i.e.\ 100~km distance) magnitude. This fragile cometary body of the initial mass of about 5000~kg exhibited many flares and disappeared at the height of 59~km above surface. The light curve can be explained assuming that the body experienced at least five subsequent sudden breakups, losing from 25\% to 99\% of its instantaneous mass in each breakup. The Bene\v sov bolide (EN\,070591, maximal magnitude $-20$) was a stony body of the initial mass of about 13\,000~kg which radiated down to 17~km of height and exhibited bright flare at 24~km. Several fragmentation events occurred below 42~km of height and are directly visible on the photographs. In both cases the spectra are composed of emission lines of the vaporized material. In addition, molecular bands are strong in Bene\v sov. \np \bc {\bf Near-Infrared Spectroscopy of the Shoemaker-Levy 9 Impact Sites with UKIRT: CO Emission from the L Site} \medskip \bi T.Y. Brooke, G.S. Orton, D. Crisp, A.J. Friedson(JPL/Caltech), G. Bjoraker(Goddard) \ei \ec \medskip Spectra of impact sites in select regions in the 3-5 $\mu$m range were obtained with the CGS4 spectrometer at the United Kingdom Infrared Telescope atop Mauna Kea, Hawaii on July 19, 20, 26, 28 UT 1994, generally long after actual impact. These are being used to determine the depth of impact effects in Jupiter's atmosphere. CO emission in the 4.7 micron fundamental vibrational band was detected at the L site on Jul 20 from 2:20-3:30 UT, over 4 hours after impact. Lines observed in emission were P4-P6 and R11-R13. Phosphine and CH$_3$D were not seen in emission. Modelling is in progress to determine CO abundances at the L site. \np \bc {\bf Limits on Polar Ionospheric Changes during the SL9 Impacts}\\[6pt] \bi Michael E. Brown\\ Lunar and Planetary Laboratory\\[6pt] \ei \ec Proposed explanations for many of the auroral and magnetospheric effects thought to be observed as a consequence of the SL9 impacts rely on a changes in polar ionospheric conductivity to transmit the effects through the magnetosphere. Observations of the Io plasma torus rotation velocity, which is controlled by this ionospheric conductivity, show that no such changes took place during the time of the impacts. The Lick Observatory observations span a three week interval centered on the impacts and reproduce 8-months of data obtained in 1991/1992. Upper limits on daily changes in the ionospheric conductivity will be presented. \np \bc {\bf Global Imaging Campaign of Shoemaker-Levy 9 Impact Phenomena}\\[6pt] \bi M. W. Buie, L. H. Wasserman, R. L. Millis (Lowell Obs.),\\ W. B. Hubbard (U. Ariz.), H. L. Reitsema (Ball Aerospace and U. Ariz.),\\ F. Roques (Paris Obs.), A. Peyrot, M. Vignand (Obs. of Les Makes),\\ E. Dunham, C. Ford (NASA/Ames),\\ H. Hammel, J. Faust (MIT),\\ K. Meech, B. Patten (U. Hawaii),\\ J. Bell, III, (Cornell), D. Toublanc (Obs. Bordeaux),\\ R. Thompson (U. Wyoming)\\[6pt] \ei \ec We deployed imaging systems to five sites for the time of the Comet Shoemaker-Levy 9 impacts on Jupiter. All sites used a combination of a high-speed optical CCD system with similar broad and narrow-band filters. Our coordinated effort covers from a few days prior to the first impact to up to five days after the last impact. Most of the data consists of multi-spectral imaging that monitors the morphology and development of the Jovian atmosphere as the impact week progressed. Other high-speed ($\sim$8 Hz) imaging sequences were taken from most sites at the time of impact to search for transient phenomena related to the impact. Some plumes were recorded through the 8900\AA\ methane-band filter but most high-speed sequences showed no changes. We will present a summary of the dataset as well as quantified searches for satellite flashes and other limits on plume phenomena. \np \bc {\bf GALILEO INFRARED OBSERVATIONS OF THE SHOEMAKER-LEVY 9 G AND R FIREBALLS AND SPLASH}\\[6pt] \bi R.W. Carlson, P.R. Weissman, J. Hui, M. Segura, W.D. Smythe,\\ K.H. Baines and T.V. Johnson\\ Jet Propulsion Laboratory\\[6pt] P. Drossart and T. Encrenaz\\ DESPA, Observatoire de Paris\\[6pt] F. Leader and R. Mehlman\\ Institute of Geophysics, UCLA\\[6pt] \ei \ec The Galileo spacecraft was fortuitously situated for a direct view of the impacts of comet Shoemaker-Levy 9 in Jupiters atmosphere and measurements were recorded by the Near Infrared Mapping Spectrometer (NIMS) instrument for several of the impact events. Seventeen discrete wavelength channels were used between 0.7 to 5.0 microns, obtained with a time resolution of 5 seconds. Two phases of the impact phenomona are found in the data: the initial fireball, which was evident for one minute, and subsequent fallback of impact ejecta onto the atmosphere, starting six minutes after fireball initiation. Preliminary analysis of the G event data shows a fireball appearing at 07:33:37 UT (as would be observed from the Earth) with a temperature of 4000 K or greater and an effective source diameter of 20 km or less. These spectra show absorption by methane and molecular hydrogen whose strength place the fireball in the upper troposphere, above the ammonia clouds. As time progresses, the fireball cools and the effective diameter increases about 2 km/sec. The strength of the hydrogen and methane absorption decreases with time, indicating that the radiating surface is rising supersonically. The fireball appears to expand adiabatically, with an adiabatic index of 1.2. After about 30 seconds, the spectra indicate a multiple temperature or opacity structure. A second phase of strong IR emission for the G event was detected beginning at 07:39:41 UT, which we interpret as impact ejecta, supersonically ejected in the fireball and plume, falling back upon the atmosphere. The resulting infrared emission steadily brightened over 2 minutes following its first detection. The timing of the event implies a minimum ejection velocity of 4 km/sec. Spectra of this splash phase suggest O-H and C-H stretch emission, perhaps from shock heated water vapor and methane. The R impact data show qualitatively similiar behavior, but with intensities reduced by a factor of two to four. \np \begin{center} \begin{large} {\bf Absolute Reflectivity Spectra of Jupiter: 0.255 - 4.0$\mu$m}\\[6pt] \end{large} \bi Chanover, N.J., Beebe, R., and Simon, A.\\ New Mexico State University\\[6pt] \ei \end{center} Imaging data from the Hubble Space Telescope (HST) and several ground based observatories are used to define a reference absolute reflectivity (I/F) spectrum of Jupiter for all latitudes. The impact of Comet Shoemaker-Levy 9 (SL9) with Jupiter in July 1994 has resulted in a tremendous amount of imaging data, primarily in the near-ultraviolet to near-infrared wavelength regime. While these new data sets undoubtedly contain vast quantities of information about Jupiter's atmosphere and its response to the comet fragment impacts, they were all obtained from different telescopes, using different instruments, by different investigators. Consequently, the calibration of all the data sets is not uniform. This makes comparisons between data sets difficult, if not impossible. We have used high-resolution SL9 Impact Campaign data from HST from 0.255 to 0.953 $\mu$m, along with near-infrared imaging data taken at the Apache Point Observatory, Palomar Observatory, and the Infrared Telescope Facility in July 1994, to create a reference spectrum of I/F as a function of wavelength for all latitudes along the ``undisturbed'' central meridian of Jupiter. This spectrum will be made available to all other SL9 investigators as a tool with which they may calibrate their own data. An example of how this I/F spectrum can be used as a calibration tool will be illustrated with February 1995 near-infrared imaging data taken at Apache Point. \np \begin{center} {\bf Galileo Direct Imaging of Impacts K, N, and W}\\[6pt] \begin{it} Clark R. Chapman and William J. Merline\\ Planetary Science Institute\\ Tucson, AZ USA\\[6pt] Kenneth Klaasen, Torrence Johnson, and Catherine Heffernan\\ Jet Propulsion Laboratory\\ Pasadena, CA USA\\[6pt] Michael J. S. Belton\\ NOAO\\ Tucson, AZ USA\\[6pt] Andrew Ingersoll\\ California Institute of Technology\\ Pasadena, CA USA\\[6pt] The Galileo Imaging Team\\[6pt] \end{it} \end{center} The Galileo camera obtained direct imaging data of the actual impact sites, showing the luminous phenomena of bolide entry and early fireball development for S-L 9 fragments K and N (using a drift scanning mode) and for W (using time-lapse imaging). All three bolides -- several-second-long initial flashes -- were of comparable brightness (a few percent of total Jupiter). But the K event showed a much brighter and longer-lasting fireball (also, possibly, a second bolide 10 seconds after the first) than did the other two events, generally consistent with the relative prominence of subsequent plume phenomena observed from Earth. Later plume development for K and W was near or below our detection limits, as were any secondary impacts during the intervals for which we returned data (with the exception of the possible second, bright K event). We will present our latest lightcurves, calibrated brightnesses, and compari- sons with groundbased data for these events. These Galileo data provide an excellent baseline for assessing Earthbased observations of early phases of other S-L 9 impacts that were observed indirectly. In general, we are confident that the onset of the luminous event we see is the bolide phase, and that precursor events seen from Earth cannot be. Precursor events must generally be either the impact of coma or much smaller, secondary projectiles (too faint to be seen by Galileo) in Jupiter's uppermost atmosphere. \newpage \begin{center} {\bf A Search for Small-Sized S-L 9 Impactors using a\\ Continuous-Readout CCD}\\[6pt] \begin{it} Clark~R.~Chapman, Carol~Neese, William~J.~Merline, Gail~Schneller, Stuart~J.~Weidenschilling, and Don~R.~Davis\\ Planetary Science Institute\\ Tucson, AZ USA\\[6pt] Philip Massey\\ NOAO\\ Tucson, AZ USA\\[6pt] \end{it} \end{center} We have performed sensitive observations of the Galilean satellites and Jupiter's morning limb to search for flashes of bolides by small, unnamed fragments of comet Shoe\-maker-Levy 9. To make the observations, we developed a technique of continuously reading the CCD under a mask that covered all but Jupiter's equatorial plane. Continuous readout allows high duty cycle and time resolution, while the mask prevents buildup of unwanted scattered- and sky-light. We cover Jupiter itself with a tiny neutral density filter. This avoids saturation of Jupiter as we clock the chip at a rate slow enough to yield adequate S/N per line on the satellites. Thus, we were able to observe Jupiter and the satellites simultaneously. The CCD is rotated such that the clocking direction is tangent to Jupiter at the impact site ($45^{\circ}$ \thinspace S). In this way, the charge from the streaked Jupiter does not overwrite the impact site, which is just off the terminator. The resultant images are long trails of Jupiter and the satellites. Scans are 2~to~17~minutes in length, with time resolution of 25\thinspace ms per CCD line. Observations were primarily done using a B filter, which we expected would give us the most sensitivity to the hot bolide phase of the impacts. The data were obtained on 8~nights at the Kitt Peak 2.1\thinspace m, including 3~nights before and during the major impacts, and 5~nights afterwards (July~16, 17, 21, 27, 28, 29, 30, 31~UT). We attempted to observe during impacts of fragments B and V. We encountered some problems due to idiosyncrasies with the modified instrumentation, but we were most affected by poor weather. We obtained data during approximately 10\% of our scheduled time. Preliminary analysis shows no obvious impacts, although we may have observed the V flash. Statistically meaningful statements about smaller fragments must await more detailed analysis of the data. \np \begin{center} {\bf Peculiarities of Spectral Evolution of SL9 Secondary Nuclei Impact Sites on Jupiter}\\[6pt] \begin{it} Churyumov K.I., Tarashchuk V.P.\\ Astronomical Observatory of Kiev University, Ukraine\\[6pt] Prokof'eva V.V.\\ Crimean Astrophysical Observatory, Ukraine\\[6pt] \end{it} \end{center} Spectral observations of Jupiter were conducted at the Crimean Astrophysical Observatory from July 2 to Aug. 30, 1994. Altogether $\sim$2000 spectra were obtained. The impacts of large fragments in the Jupiter atmosphere caused powerful outbursts that led to complete evaporation of a penetrated body as well as to heating of the surrounding atmosphere . Because the comet fragment was surrounded by a coma that comprised products of evaporation of the cometary matter and dust, then the region of penetration of cometary matter in the atmosphere occupied much more space, than the place of the outburst and heating. Thus in the impact sites there had to be luminosity of the evaporated cometary matter as the result of the outburst yielding spectral lines that are absent in the Jupiter spectrum, and the spectrum of the atmosphere itself had to undergo changes. The second effect of the penetration of the fragment surrounded by the atmosphere could be appearance of certain emissions not only in the site of the impact but at substantial distances from it as well. Analysis of the spectra obtained in the Crimean Astrophysical Observatory allowed to detect a number of peculiarities in the sites that appeared after the fall down of cometary fragments in the form of dark spots. Spectral variability on temporal scales of tens of seconds was registered in the sites of the impacts of the comet fragments 1 or 2 revolutions of Jupiter later after the impact moments in the atomic lines and molecular bands of the Jupiter atmosphere (NH3 , CH4 , H2 and H). Intensities of the lines and bands also showed changes from spot to spot . Thus in the spot spectrum that was caused by the fragment A impact observed 2.2 revolutions of Jupiter , the biggest variability occurred in the region of the CH4 band. Variability in the region of quadruple line of molecule H2 was registered when the impact site from fragment H crossed the central meridian of Jupiter after 1.3 revolutions of the latter. Repeated variability in the region of resonance line of Na at 589-589.6 nm as well as in the region of the band of NH3 was registered several times. Occasionally variability in the lines of Li at 670.8 nm, Ca at 643.9 nm and H2 at 656.3 nm occurred. Successive in time occurrence of variability in different ranges of the spectrum are observed. And all this allows to suggest stratification of outburst products and different excitation temperatures that gives the basis for seeking possible regularities. Variability of Na with a big Doppler shift that was observed in several cases is evidence of a complex picture of moving matter in the new spots. Preliminary estimations of velocities of some jets of matter gave the value 300-600-1000 km/sec, here the velocity vector had the direction both along the ray of the sight and in the opposite direction. \newpage \bc {\bf Hubble Space telescope Far-Ultraviolet Imaging of Jupiter During the Impacts of Comet Shoemaker-Levy~9}\\[6pt] \bi John T. Clarke(1), Renee Prange(2), Gilda Ballester(1), John Trauger(3),\\ Robin Evans(3), Karl Stapelfeldt(3), and Wing Ip(4)\\[6pt] \ei \ec \bi (1) University of Michigan\\ (2) CNRS - Universite de Paris, Orsay\\ (3) Jet Propulsion Laboratory\\ (4) Max Planck Institut fur Aeronomie\\[6pt] \ei Hubble Space Telescope far-ultraviolet images of Jupiter during the Shoemaker-Levy 9 impacts show the impact regions darkening over 2-3 hours post-impact and darker and more extended than at longer wavelengths, indicating UV-absorbing gases or aerosols more extended, more absorbing, and at higher altitudes than the visible absorbers. Transient auroral emissions were observed near the magnetic conjugate point of the K impact site just after that impact. The global auroral activity was fainter than average during the impacts, while a variable auroral emission feature was observed inside the southern auroral oval preceding the Q1/Q2 impacts. \np \begin{center} {\Large\bf An Update on Imaging Observations from McDonald Observatory} \\ [15pt] \parbox{11cm}{ A.~L.~Cochran, B.~J.~Armosky, C.~E.~Pulliam, B.~E.~Clark, W.~D.~Cochran, M.~Frueh, D.~F.~Lester, L.~Trafton (U. Texas), Y.~Kim (U. Maryland), C.~Na (SWRI), W.~Pryor (LASP)} \end{center} During and shortly after the impact of SL9 into Jupiter, we obtained imaging data using the 0.8-m telescope and CCD detector, and 2.7-m telescope and HgCdTe detector at McDonald Observatory. We present here further analysis of imaging observations which were obtained during the impacts. We observed the impact of the R fragment into Jupiter and present optical and IR light curves. In addition, we have continued to obtain CCD images of Jupiter since the impact, including observations in January through March 1995. We will examine how the impact sites have varied with time. \newpage \begin{center} {\bf High Resolution CCD Spectroscopy of the Comet Shoemaker-Levy~9 Impact Locations on Jupiter}\\[6pt] \begin{it} William D. Cochran (University of Texas), Kevin H. Baines (JPL) Chan Na (SWRI), and Wayne Pryor (LASP) \end{it} \end{center} We used the McDonald Observatory 2.7m telescope 2Dcoud\'e cross-dispersed echelle spectrograph to obtain high resolution ($R = 60,000$) spectroscopy of Jupiter over the 4000-10000{\AA} region during and immediately after the impacts of the fragments of Comet Shoemaker-Levy~9 on Jupiter. The spectrograph entrance aperture of $8.2 \times 1.2$\,arcsec allowed us to obtain spatially resolved spectra of the impact spots and the surrounding undisturbed regions of the Jovian atmosphere. We model the observed H$_2$, NH$_3$ and CH$_4$ lines in order to derive the altitude and optical thickness of the stratospheric haze caused by the impacts as a function of wavelength and of time. We also present results of a search for absorption by H$_2$O in the visible spectrum. \newpage \bc {\bf Jovian Acoustics and Gravity Waves}\\[6pt] \bi Michael D. Collins and B. Edward McDonald\\ Naval Research Laboratory, Washington, DC 20375\\[6pt] W. A. Kuperman\\ Scripps Institution of Oceanography, La Jolla, CA 92093\\[6pt] William L. Siegmann\\ Rensselaer Polytechnic Institute, Troy, NY 12180\\[6pt] \ei \ec We have modeled the propagation of acoustic and gravity waves from the impact sites of Comet Shoemaker-Levy 9 using a three-dimensional technique that accounts for spatial variations in sound speed, BV frequency, density, and wind velocity. The zonal winds act as horizontal waveguides that pinch the propagating energy into beams that remain coherent all the way around Jupiter. Since the energy in the beams is enhanced by about an order of magnitude, they indicate the most favorable locations to look for evidence of waves far from the impact sites. It has been established that gravity waves appear near the impact sites in HST images [H. B. Hammel et al., Science 267, 1288-1296 (1995)]. Some of the HST images also show evidence of an outward moving front that is at a location consistent with the group speed of an acoustic wave. \np \bc {\bf Palomar Mid-infrared Spectroscopic Observations of Comet Shoemaker-Levy 9 Impact Sites}\\[6pt] \bi B.J. Conrath\\ NASA/GSFC\\[6pt] P.J. Gierasch, T. Hayward, C. McGhee,\\ P.D., Nicholson, \& J. Van Cleve\\ Cornell University\\[6pt] \ei \ec Post impact spectra between 8 and 14 micrometers of the Shoemaker-Levy 9 impact sites and surrounding regions, acquired with SpectroCam-10 on the Hale telescope, are analyzed. Both direct modeling and inversion techniques are used to infer information on Jovian atmospheric composition and thermal structure from these observations. In the days immediately following the impacts, over areas with diameters of approximately 2000 km centered on the sites, stratospheric temperatures are found to be elevated relative to adjacent, unperturbed areas. A parameterized retrieval of the vertical distributions of ammonia and phosphene indicate that these gases are substantially enhanced in the stratosphere, and strong stratospheric emission from ethylene is also observed. The temporal behavior of the retrieved atmospheric parameters associated with sites K and L over a 5-day post impact period is summarized. Stratospheric aerosol opacity in the 10-micrometer region is presented. Finally, implications of these results concerning the radiative and dynamical processes associated with the sites are considered. \np \bc {\bf Near-Infrared Imaging Spectroscopy of the Impacts of SL9 Fragments C, D, G, K, N, R, V, and W with Jupiter}\\ \bi D. Crisp (JPL) and V. Meadows (NRC/JPL)\\[6pt] \ei \ec We used the InfraRed Imaging Spectrometer (IRIS) on the Anglo-Australian Telescope to observe the collisions of 8 of the Comet Shoemaker-Levy 9 fragments with Jupiter. We also monitored the evolution of the impact sites from 16 to 23 July, 1994. Spatially-resolved K--band (1.98--2.38 $\mu$m) spectral image cubes were collected during the C, D, G, K, R and W impact events. An H--band (1.4--1.8\,$\mu$m) image cube was also collected during the Fragment K impact event. Fast-rate 2.35 $\mu$m filter photometry was used to monitor the impacts of fragments N and V. The IRIS image cubes provide a spectral resolution of 300 ($\lambda/\Delta\lambda$), a spatial resolution of 0.6$^{\prime\prime}/$pixel, and a temporal resolution of $\sim 2$ minutes or less ($\sim 30s$ for fragment K). These observations therefore provide detailed descriptions of the impact events, from the time the fragments entered the Jovian atmosphere, until their collapsed plumes crossed the limb and traversed the day side of Jupiter. Many of the AAT/IRIS observations were simultaneous with Galileo or HST observations, facilitating comparisons among these data sets. Each event was first detected as one or more faint flashes (precursors). The G and K precursors were first detected 0.5 to 1.5 minutes before the impact fireball was observed by instruments on the Galileo spacecraft. We acquired spectra of both the first (entry) precursors, and second (fireball) precursors for fragments C and K. The first precursors' spectra were dominated by blue continuum emission. The second precursors' spectra were much redder, and exhibited enhanced CH$_4$ absorption features at 2.20, 2.32 and 2.70 $\mu$m as they faded. These precursors were followed 5--10 minutes later by a much brighter ``main flash" which peaked 8-15 minutes after the second precursor. The main flashes were also initially dominated by continuum emission with color temperatures decreasing from $>$500 to $\sim230$\,K. Weak CO absorption at wavelengths $>2.3$\,$\mu$m was also occasionally detected during the initial phase of the main flashes. As the intensities of the main flashes peaked and started to fade, our spectra revealed strong line emission by CO ($\lambda > 2.29 \mu$m), NH$_3$ (2.03\,$\mu$m), CH$_4$ (2.20\,$\mu$m) and H$_2$O (2.0 and 2.3\,$\mu$m). H$_2$ (2.122\,$\mu$m) quadrupole emission was also detected during the decay of the the C and D flashes. The CO line emission indicated rotational temperatures $>2000$\,K. Thirty minutes after each impact, there was little or no evidence of CO, H$_2$, or H$_2$O absorption and emission in our spectra of the impact clouds. The initial dominance of continuum emission over line emission in the main infrared flashes suggests emission from hot particulates rather than gases in the rising impact plume. CO seen in absorption in the initial phases of the main flash may have been transported upwards in the expanding, cooling, fireball. The hot CO, NH$_3$ and H$_2$O seen during the decay of the main flash are indicative of a `splashback' event as the plume collapsed. Emission rates, and an estimate of the total abundance of emitting molecules will be presented. A radiative transfer model was also used to estimate the altitude and particle properties of the impact clouds. The spectra of the impact sites several hours after impact can be simulated by an optically-thin ($\tau$\,$>$\,0.25) cloud consisting of small ($\sim$\,0.25\,$\mu$m),reflective ($\omega$\,$>$\,$0.97$) particles, located above the 1\,mbar level. \np \bc {\bf THE R-IMPACT: FLASHES AND FIREBALLS, WHAT DID WE SEE?}\\[6pt] \bi Imke de Pater, P. Nicholson, K. Zahnle, J. R. Graham, G. Jernigan,\\ T. Hayward, G. Neugebauer, K. Matthews, A. Weinberger,\\ M. Liu, M. Brown\\[6pt] \ei \ec The R-impact was observed at 2.3, 3.2 and 4.5 $\mu$m with the Keck and Palomar telescopes respectively. We will show a comparison of the various datasets, and compare the event times with the timing of the flashes observed by the Galileo spacecraft. Based upon the viewing geometry and timing of the various events, we suggest the following quantitative scenario for the sequence of events. Given the timing of {\it Flash 1}, it must be related to the comet's entry into Jupiter's atmosphere. The time evolution of the flash is very similar at the three wavelengths; it lasts for about 40 seconds and the flux ratios are consistent with a temperature of $\sim 1000$ K. We suggest it is the meteor trail seen about 400 km above Jupiter's cloud deck. The duration of the trail is indicative of the cooling time of the heated trail high up in the atmosphere, or it may suggest the comet fragment to be broken up into a string of material about 2000 km in extent. {\it Flash 2}, starting approximately one minute after the first flash appeared, has a rapid rise time at all three wavelengths. This flash is roughly 20 times brighter at 4.5 $\mu$m than at 2.3 $\mu$m. We attribute the second flash to thermal emission from the fireball rising above the limb of Jupiter. The decay, presumably indicative of adiabatic cooling, is slow at 2.3 $\mu$m ($\sim$ 3 min), but quite fast at 4.5 $\mu$m ($\sim$ 30 sec). This is just opposite to what one would expect for a slowly cooling fireball, and is not yet explained. Galileo saw its first flash $\sim15$ seconds before Keck and Palomar saw the second flash. Since Galileo NIMS had a direct view of the impact site, it was able to see the fireball well before Earth-based observers. The evolution of the third and brightest {\it flare} is similar at all three wavelengths. We attribute this flare to a high atmospheric temperature ($T\approx 600$ K) induced by the release of gravitational potential energy by fireball material raining down onto the atmosphere. The beginning of the flare was also seen by Galileo. A fourth peak seen 10 min after the main flare is similar to those reported from the H and L impacts. At optical wavelengths, HST observed several plumes (A, E, G and W) in reflected sunlight. Although the infrared flares and HST plumes are generally seen at the same time, we believe that they represent different aspects of the same elephant. \np \bc {\bf THE OUTBURST OF JUPITER'S SYNCHROTRON RADIATION FOLLOWING\\ THE IMPACT OF COMET P/SHOEMAKER-LEVY 9}\\[6pt] \bi Imke de Pater, C. Heiles, M. Wong, F. van der Tak, R. Millan (UCBerkeley),\\ R.J. Maddalena (NRAO Green Bank) M.K. Bird, O. Funke (Univ. of Bonn),\\ J. Neidhoefer (MPI Bonn), R. M. Price, M. Kesteven (CSIRO, Australia),\\ M.J. Klein, S.J. Bolton (JPL), R.S. Foster (NRL),\\ S. Sukumar (DRAO,Penticton), R.G. Strom (NFRA, Dwingeloo),\\ R.S. LePoole (Leiden Univ., Netherlands),\\ R.W. Hunstead(Sydney Univ, Australia)\\[6pt] \ei \ec Jupiter's microwave emission was observed since well before the SL9 impact by many different telescopes. We present the total intensity data at wavelengths between 6 and 90 cm (an improved subset of the data published by de Pater et al., 1995, submitted to Science, Dec. 1994). The flux density increased, depending on wavelength, by 10--45\% during the week of impacts, and the radio spectrum hardened. Following the week of cometary impacts, the flux density began to subside at all wavelengths, while the spectrum continued to harden. The flux density was still declining in February 1995. We suggest that the increase in flux density is caused by energization of the resident particle population. The evolution of the radio spectrum after the SL9 encounter may be caused by an enhancement in the amount of magnetospheric dust, due to the break-up and ``outgassing'' of the comet. The radio flux density measurements may be the only dataset sensitive enough to determine the amount of cometary dust injected into the magnetosphere. As such, the radio data provide a unique probe of radial diffusion in Jupiter's magnetosphere. We show the time evolution of the brightness distribution of the radio emisison as observed by the VLA and the WSRT telescopes. A preliminary reduction and analysis of the VLA images shows, crudely, the following phenomena: {\bf a}) The enhancement in Jupiter's flux density is, initially, dominated by an enhancement in the magnetic equator at longitudes $\lambda_{III} \approx 160-260^\circ$, in the socalled {\it active sector}. {\bf b}) There is {\it no} obvious connection with the impact sites or times. {\bf c}) The radiation peak which brightened is often (but not necessarily always) displaced inwards, closer to Jupiter. This suggests that radial diffusion plays some role and that (part of) the increase in the radio emission can be explained through electron energization by conservation of the first adiabatic invariant. {\bf d}) The impact-induced asymmetry between the peaks lasts for less than 4 days, as expected from the energy dependent drift period of the energetic particles. \np \begin{center} {\bf Flaring-up Splitting of SL9 after Encounter with Jupiter}\\[6pt] \begin{it} E.M. Drobyshevski\\ Ioffe Physico-Technical Inst.\\ 194021 St.Petersburg, Russia\\ E-mail: emdrob@drob.pti.spb.su\\[6pt] \end{it} \end{center} Assumption of tidal disruption of SL-9 contradicts numerous data: it lasted months after the perijove passage, the fragments' velocity depended on their size, etc. One can hardly explain why this breakup should be distinguished from rather common breakups of other comets far from planets. Such breakups are believed to be caused by the inner energetics of comets and they correlate with a flare comet activity which, in its turn, is tied somehow with the Solar activity. The inner energy sources of SL-9 were triggered likely by the same cause that initiates the sources in comets when they cross sector structure boundaries in the Solar wind, viz. by electric current flown through the SL-9 nucleus when it found its way deep into the Jovian magnetosphere and ~100 kV e.m.f. was induced across the nucleus (recall that 400 kV e.m.f. induced across Io generates ~5 MA current). What an energy source is required for: (1) being initiated by the current, (2) being capable of imparting ~1 m/s velocity to ~1 km fragments, and (3) being active in them during months? The only option reported thus far could be the dirty ice saturated with its electrolysis products and so capable of burning and even detonation when some additional energy is supplied. This hypothesis is proved to be fruitful as for numerous minor bodies' origin understanding, explanation of SP comet energetics and chemistry, including their distant outbursts etc, and for explanation why in SL-9 fragments and in plumes originated after their infall onto Jupiter no water traces were detected. Here water could evaporate due to electrolized ice outburning before discovery of SL-9 and its hitting Jupiter. \newpage \begin{center} {\bf Lithium Presence in Impact Plume Favors the Planetary Origin of SL9 }\\[6pt] \begin{it} E.M. Drobyshevski\\ Ioffe Physico-Technical Inst.\\ 194021 St.Petersburg, Russia\\ E-mail: emdrob@drob.pti.spb.su\\[6pt] \end{it} \end{center} Lithium is one of the less abundant elements. Its detection in SL-9 L fragment plume has risen a number of questions. Two ones are main: (1) why was Li observed never before, even it Sun-grazers, and (2) why was it localized in some portion of the SL-9 ice only? The great localized Li overabundance can be hardly explained in framework of standard hypotheses on the primary cometary grains' formation in turbulized gaseous medium. The New Eruptive Cosmogony (NEC) of minor bodies considers the SP comet nuclei to be fragments of icy envelopes of Ganymede-type bodies. Such ice accumulates its electrolysis products 2H2+O2 as the solid-state solution. On reaching their ~15-20 wt.% concentration, it can explode being initiated by the meteoroid impact. The local Li concentration in comet ice can be understood from the NEC standpoint if one takes into account geochemical processes occurring inevitably in parent planetary bodies. These processes involve at first an igneous concentration of Li in acid and sedimentary rocks of the rocky core crust and, afterwards, the aqueous washing out and electrolytic transport of Li compounds into the water-ice mantle. These compounds are accumulated there in the last salt brine resting after the water freezing (or evaporation). By this way Li can be accumulated in the form of separate ore nests near the rocky core surface and in the ice envelope. Thus, in the context of NEC, it is not surprising that Li occurs to be concentrated only in a small part of far from all the cometary nuclei. \newpage \centerline {\bf Changes in Flux and Brightness of Jupiter's Synchrotron Radiation} \centerline {\bf During and After SL-9 Impacts} \vskip 5mm \centerline {\it George A. Dulk$^{1,2}$, Yolande Leblanc$^1$ and Richard W. Hunstead$^3$} \medskip \centerline {$^1$DESPA, Observatoire de Paris, 92195 Meudon, France.} \centerline {$^2$University of Colorado, Boulder, CO 80309-0391, U.S.A.} \centerline {$^3$University of Sydney, Sydney, NSW 2006, Australia} \vskip 5mm The Australia Telescope and the Molonglo Observatory Synthesis Telescope were used to observe Jupiter before, during and after the impacts of SL-9. Integrated flux and 2-D images of Jupiter's synchrotron radiation belts were produced with a resolution of $4''\times 18''$ at 13~cm, $7''\times 30''$ at 22~cm and $43''\times 200''$ at 36~cm. Starting about one day after the first impact and reaching a peak soon after the time of the last impact, the integrated flux density increased by approximately 30\% at 13~cm, 25\% at 22~cm and 40\% at 36~cm. Before the impacts, at 22~cm, the images were similar to those observed at 20~cm by the VLA 12 years earlier at the same longitudes. During and after the SL-9 impacts the belts were brighter than before, and remained bright at least 12~days after the first impact. The increase in brightness was almost entirely confined to one hemisphere, between about 100$\deg$\ and 240$\deg$\ longitude. The changes in the belts at 13~cm were similar to those observed at 22~cm. The new asymmetry implies the existence of a new or newly-accelerated population of relativistic electrons confined to a portion of the magnetic field of the planet. \newpage \bc {\bf Abundances of NH$_3$ and CS$_2$ and Upper Limits of H$_2$S, PH$_3$, C$_2$H$_2$, and C$_2$H$_6$ Above the SL9/G Impact Site}\\[6pt] \bi S.G. Edgington and S.K. Atreya\\ Department of Atmospheric, Oceanic and Space Sciences\\ University of Michigan, Ann Arbor, MI 48109-2143\\[6pt] L.M. Trafton Department of Astronomy\\ University of Texas, Austin, TX, 78712\\[6pt] J.J. Caldwell\\ Institute for Space and Terrestrial Science\\ Space Astrophysics Lab., 4850 Keele St., North York, ON, M3J 3K1\\[6pt] K.S. Noll and H.A. Weaver\\ Space Telescope Science Institute\\ 3700 San Martin Drive, Baltimore, MD 21218\\[6pt] \ei \ec Two-stream radiative transfer models allowing for anisotropic scattering were used to fit the July~18, 1994 Hubble Space Telescope/Faint Object Spectrograph 170--230~nm observations of Jupiter above the G-impact site. Aerosol unit optical depths were varied to occur within 0.3--10~mb and the refractive index was varied to account for a range of possible aerosol materials. The models yield abundances for NH$_3$ and CS$_2$ of $(0.25-1.3) \times 10^{16}$~cm$^{-2}$ and $(0.43-1.1) \times 10^{15}$~cm$^{-2}$, respectively, at the unit optical depth level in the part of the atmosphere above the G-impact site. The upper limits of H$_2$S, PH$_3$, C$_2$H$_2$, and C$_6$H$_6$ at the unit optical depth level are $1.2 \times 10^{16}$~cm$^{-2}$, $3.3 \times 10^{14}$~cm$^{-2}$, $1.0 \times 10^{17}$~cm$^{-2}$, and $3.3 \times 10^{14}$~cm$^{-2}$, respectively. \np \begin{center} {\bf Near-Infrared Spectroscopy of Jupiter at the Time of Comet \mbox{Shoemaker-Levy 9} Impacts: Emissions of CH$_{\bf 4}$, H$_{\bf 3}^{\bf +}$ AND H$_{\bf 2}$}\\[6pt] \begin{it} Th.Encrenaz and P.Drossart (DESPA, Obs.Paris), R.Schulz and J.A.Stuewe (MPIA Lindau), G.Wiedemann (ESO, Garching), and J.Crovisier (ARPEGES, Obs.Paris)\\[6pt] \end{it} \end{center} Near-infrared emissions of the SL9 impact sites of Jupiter have been recorded on July 16-18, 1994, using the IRSPEC imaging spectrometer at the 3.5m NTT of ESO (La Silla, Chile). A very strong emission of methane was recorded between 3.50 and 3.56 microns, shortly after impact H, showing evidence for a strong and temporary increase of the Jovian stratospheric temperature. Emissions of H2 (2.12 microns) and H3+ (3.53 microns) werew detected above some of the impact sites, several hours after the impacts. A strong continuum was also detected at 2.12 microns over the impact sites, presumably due to intense scattering of reflected sunlight by high-altitude stratospheric haze. \newpage \begin{center} {\bf Infrared Heterodyne Observations of NH$_{\bf 3}$ and C$_{\bf 2}$H$_{\bf 6}$ After The Collision of Comet \mbox{P/Shoemaker-Levy 9} With Jupiter}\\[6pt] \begin{it} K. E. Fast(UMD), T. Kostiuk(NASA/GSFC), F. Espenak(NASA/GSFC), D. Zipoy(UMD),\\ D. Buhl(NASA/GSFC), T. A. Livengood(UMD), G. Bjoraker(NASA/GSFC),\\ P. Romani(NASA/GSFC), J. Goldstein(SI/NASM)\\[6pt] \end{it} \end{center} Spectra were taken with the Goddard Infrared Heterodyne Spectrometer during the NASA/IRTF observing campaign of the collision of comet P/Shoemaker-Levy 9 with Jupiter. Stratospheric NH3 emission was observed at a number of impact regions days after the collisions. The true line shapes, obtainable with this instrument, indicate NH3 emission from between 1 and 10 mbar at the impact regions. Stratospheric C2H6 emission was also observed along the impact latitude. Preliminary analysis and conclusions will be presented, along with the results of follow-up measurements made in March '95. \newpage \begin{center} {\bf HST Observations of Mg$^{\bf +}$ and Dust in Outburst \\ from Comet P/Shoemaker-Levy 9}\\[6pt] \begin{it} P. D. Feldman (JHU), H. A. Weaver (STScI), D. C. Boice (SWRI),\\ S. A. Stern (SWRI), M. A. McGrath (STScI)\\[6pt] \end{it} \end{center} Ultraviolet spectroscopy of SL9 was performed on three different occasions between July 1993 and July 1994 (Weaver \etal\ 1994, 1995) using the Faint Object Spectrograph (FOS) of the Hubble Space Telescope with the primary objective to search for the hydroxyl radical (OH) as a tracer of water ice in the SL9 fragments. Although OH was not detected during these spectroscopic investigations, strong \Mgtwo\ emission near 2800~\AA\ was observed in the vicinity of fragment G during a very short outburst on 14 July 1994. The emission decayed with a time constant of about one minute. Approximately 18 minutes after the \magplus\ outburst, the continuum spectrum of dust scattered sunlight also changed dramatically, increasing by more than a factor of three over an 8~minute period and then relaxing back to the quiescent level less than 20 minutes after the start of the outburst. The enhanced continuum also exhibited a strong reddening, $\sim$13\% per 100 \AA , compared with a flat solar spectrum for the quiescent dust. The two lines in the \Mgtwo\ doublet are partially resolved in the HST spectrum, indicating that the emission was strongly peaked within a spatial region of $\sim$1000 km and suggesting ion sputtering of the dust surrounding the fragment as a possible source mechanism. This structure also excludes the possibility of the \Mgtwo\ emission arising from a terrestrial atmospheric source. At the time of these observations the comet was \mbox{$3.8 \times 10^{6}$ km} away from Jupiter, which is consistent with the expected location of the magnetopause. Neutral Mg was not detected, although the strong \Mgone\ resonance transition at 2853 \AA\ was in our bandpass. Quantitative estimates of the amount of mass released in these two events and physical constraints on possible source and loss mechanisms will be presented.\\ References:\\ H. A. Weaver \etal, 1994. {\it Science} {\bf 263}, 787. \\ H. A. Weaver \etal, 1995. {\it Science} {\bf 267}, 1282. \\ \newpage \begin{center} {\bf Calibrating groundbased observations of the SL-9 impact clouds with small telescopes using the HST WFPC2 images as 'ground truth'}\\[6pt] \begin{it} Daniel Fischer\\ Planetary and Cometary Observers Group\\ Germany\\[6pt] Carlos Hernandez\\ Association of Lunar and Planetary Observers\\ U.S.A.\\[6pt] \end{it} \end{center} While the images from the HST have undoubtedly the highest angular resolution, the temporal coverage of the evolution of the impact clouds on Jupiter is very uneven and displays large gaps; furthermore, due to sun proximity concerns no images could be obtained for many months after late August. In contrast, a tremendous network of dedicated amateur observers was following the developments on Jupiter almost minute by minute for months, and it has been suggested that these CCD images and drawings with small telescopes form a valuable resource for our understanding of both the impact physics and the wind motions on Jupiter (Limaye, AGU Fall Meeting 1994). We are comparing archival HST WFPC2 images with simultaneous amateur observations to determine the precision and general reliability of the latter and to arrive at rules one should follow in interpreting them. \newpage \bc {\bf Near-IR Spectral Images from WIRO using the U. of Rochester Array of Jupiter during Comet Shoemaker-Levy 9 Impact Interval}\\[6pt] \bi Brendan Fisher, Judith Pipher, William Forrest, \& Eric Howard\\ U. Rochester\\[6pt] Chick Woodward \& Bob Howell\\ U. of Wyoming\\[6pt] Bob Gehrz\\ U. of Minnesota\\[6pt] \ei \ec The University of Rochester Infrared group, in collaboration with the University of Wyoming and the University of Minnesota collected a large set of near-IR image data of Jupiter in July 1994 from the 2.3-m telescope at the Wyoming Infrared Telescope Facility using a 256x256 InSb array. We obtained a large number of images in the 1.6-2.3 and 2.9-4.0 micron bands with two CVFs with a spectral resolution of 2%. Additionally, the planet was imaged in the J, H, K, L', and M' (4.67) bands. The B, U, and V impacts were observed but no effects were seen in the preliminary analysis. Other sites were observed after the impacts as permitted. We have observed an unusual spectral emission in the Q1 spot near 3.35 microns during its first transit that was not visible in other spots visible on the disk at the same time. Other preliminary results and progress will be presented along with a summary of our spectral-temporal coverage. \np \begin{center} {\bf Optical spectroscopy of atomic emission from the L and Q$_1$ impacts on Jupiter}\\[6pt] \begin{it} A. Fitzsimmons, J. E. Little \\ Queen's University of Belfast \\ Belfast, UK\\[6pt] P.J.Andrews, R.Catchpole, N.Walton \\ Royal Greenwich Observatory \\ Cambridge, UK \\[6pt] I.P.Williams \\ Queen Mary \& Westfield College\\ London, UK\\[6pt] \end{it} \end{center} During the impacts of fragments L we observed the associated low-resolution optical spectrum at wavelengths 350nm-670nm. The spectra demonstrate the existence of neutral Na, Fe, Mg, Ca and Mn in the plume, which we identify as remnants of the vapourised bolide. The following night we also obtained high-resolution spectra of Na D doublet emission resulting from the impact of fragment Q1. We have constructed models that are able to explain the observed emission line intensities. We will present our latest modelling of the temperatures and column densities of the various atomic species observed. \np \bc {\bf Model Calculations of Aerosol Particle Mean Radius and Number Density Formed in Comet SL-9 Fireballs}\\[6pt] \bi A.J. Friedson, R.A. West, and K.H. Baines\\ JPL/Caltech\\[6pt] \ei \ec We present calculations of the mean radius and number density of particles condensing in a fireball expanding along a moist adiabat, for various assumed compositions for the aerosol. The initial mass of condensible vapor in the fireball is an important parameter. Relatively volatile species such as ammoniatend to form particles less than a few tenths of a micrometer in radius; refractory species generally produce particle radii greater than 1 micrometer. We estimate the optical depth of plumes seen above Jupiter's limb at visible and near-IR wavelengths for different cases of composition and vapor mixing ratio. \np \begin{center} \LARGE Long Term Monitoring of Jupiter's Synchrotron Radiation with the Nan\c{c}ay Radiotelescope at the Time of the Collision with Comet P/Shoemaker-Levy 9 \vspace{1cm} \\ \large Patrick H. M. GALOPEAU, Eric GERARD \\ and Alain LECACHEUX \vspace{1cm} \\ Observatoire de Paris, URA CNRS 1757 \\ 5, Place Jules Janssen, F-92195 Meudon Principal Cedex, France \vspace{2cm} \end{center} The jovian synchrotron emission has been monitored with the Nan\c{c}ay radiotelescope at 1410 MHz, 1666 MHz and 3300 MHz from 1 April 1994 to 23 February 1995. Between 13 July and 26 July 1994, we have observed a 20 \% increase of the non-thermal flux at 1410 and 1666 MHz but a 40 \% increase at 3300 MHz. In February 1995, the non-thermal fluxes at the three frequencies are still 50 \% above the pre-encounter levels. There is no significant change of the beaming curve during the pre- and post collision periods. The possibility of changes in the degree of linear polarization and source size are investigated. \newpage \begin{center} {\bf Multi-Filter Optical Observations of SL9 Impact Spots on Jupiter}\\[6pt] \begin{it} Galen Gisler\\ Los Alamos National Laboratory\\[6pt] Bryan Laubscher\\ Amparo Corporation\\[6pt] Nancy Chabot\\ Los Alamos National Laboratory\\[6pt] Kirsten Boudreaux and Randy Grashuis\\ University of New Mexico\\[6pt] \end{it} \end{center} The 24-inch telescope of the Capilla Peak Observatory of the University of New Mexico was used to observe Jupiter during the week of the impact of comet Shoemaker-Levy-9 onto Jupiter. Images of Jupiter were obtained in several narrow-band interference filters. The opacity in the spots is calculated as a function of wavelength, and used to infer the distribution of the debris with altitude. The debris is found to reside very high in the aerosol layer above the visible cloudtops. \newpage \bc {\bf IRTF Impact Imaging Results}\\[6pt] \bi J. D. Goguen, A. J. Friedson, G. S. Orton\\ JPL\\[6pt] The IRTF Science Team\\[6pt] \ei \ec Highlights of the IRTF results are published in the special issues of {\it Science\/} and {\it Geophysical Research Letters}. This poster will include some of those highlights pertaining to impact imaging of precursors and plume evolution, but will focus on aspects of the impact data set not previously reported. The IRTF acquired useful data for the B, C, F, G, and R impacts. \np \bc {\bf Mid-IR Spectroscopy and NH$_3$ and HCN Images of K Impact Site}\\[6pt] \bi C.A. Griffith (N.~Arizona~U.), B. B\'ezard (Paris-Meudon Obs.), D. Kelly (U.~Texas),\\ J. Lacy (U.~Texas), T. Greathouse (N.~Arizona~U.), \& G. Orton (NASA/JPL)\\[6pt] \ei \ec We present observations of SL9 comet's crash that were taken at the NASA Infrared Telescope Facility (Mauna Kea, Hawaii), with the U. Texas mid-infrared echelle spectrometer IRSHELL. This is a 21 spatial by 64 spectral array, with a step size of 0.8 arcsec. Observations were conducted at a spectral resolution of $\sim$15000. We detected ammonia emission at wavelengths of 908 and 948 cm$^{-1}$ over the K impact site at several times after impact: 20 hours, 5 days and 10 days later. HCN emission was observed 10 days after impact. With each detection, both the NH$_3$ and HCN emission lines were imaged with a resolution of 1.4 arcsec over a 17 by 6 arcsec swath centered on the K impact site. At the impact site the ammonia lines were best interpreted with a distribution mostly above 10 mbar, having a column density of $2-5 \times 10^{17}$ molecules cm$^{-2}$ above 40 mbar. We have derived both vertical information and horizontal distributions for NH$_3$ and HCN. The inferred HCN abundance is sensitive to the temperature profile, which was derived from C$_2$H$_2$ and CH$_4$ line spectra (see poster by B\'ezard \etal). We observe the ammonia spreading out over a larger horizontal area with time. Its distribution is depleted with time as a function of altitude, consistent with photochemical destruction (Moses \etal 1995). The vertical distribution of the NH$_3$ appears consistent with dynamical models of the explosion (K. Zahnle, priv. comm.). \np \bc {\large\bf Microwave Imaging of Jupiter's Troposphere\\ During Impact with Comet P/Shoemaker-Levy~9}\\[6pt] \bi A.~W. Grossman and S.~M.~White (Univ. of Maryland),\\ D.~O.~Muhleman and M.~A.~Gurwell (Caltech)\\[6pt] \ei \ec We report on the results from a world-wide campaign to acquire high-resolution, microwave images of thermal emission from Jupiter's troposphere, before, during, and after impact with fragments of comet P/Shoemaker-Levy 9. Interferometric observations were obtained at wavelengths of 3cm and 6cm from the Very Large Array (VLA) and the Australia Telescope (AT). At these wavelengths, gaseous ammonia is the primary source of opacity in Jupiter's troposphere. It is also the principal condensate. Therefore changes in brightness temperature are indicative of changes in ammonia abundance and relative humidity. The corresponding weighting functions at these wavelengths probe the pressure levels 1-10 bars, below the optically thick cloud deck. Preliminary images at centimeter wavelength clearly show the expected zone-belt structure. Two prominent features in the radio data are a distinctly bright band at the position of the North Equatorial Belt (NEB) and a corresponding dark band at the position of the Equatorial Zone (EZ). The 30K brightness temperature difference (at a wavelength of 6cm) between these two regions, interpreted within the context of a radiative transfer model, requires that the NH${}_3$ mixing ratio decrease by a factor of two from the EZ to the NEB. At the latitude of the impacts there are no discernible features at a level of 3-5K within a 3000-5000 km beam-width. This constrains the change in the average NH${}_3$ abundance within this region to value of less than 10\%, although larger changes in NH${}_3$ abundance are allowed in a smaller region. These limits may constrain the depth of penetration of the comet fragments. Work continues to reduce the full complement of data taken during the week of impacts and to improve the sensitivity and quality of the images. \np \bc {\bf EUVE Observations During the Comet Shoemaker Levy/9 Impacts}\\[6pt] \bi D. T. Hall\\ Center for Astrophysical Sciences\\ The Johns Hopkins University\\ Baltimore, MD~21218\\[6pt] G. R. Gladstone\\ Southwest Research Institute\\ 6220 Culebra Road\\ San Antonio, TX~78228\\[6pt] \ei \ec The Extreme Ultraviolet Explorer satellite conducted extensive observations of the Jupiter system before, during and after the arrival of the fragments of Comet Shoemaker-Levy/9. Approximately 500,000 seconds of data were acquired in 1994. Previous observations of the Jupiter system revealed that electron-impact generated line emission from oxygen and sulfur ions resident in the Io plasma torus dominate the spectrum in the 37 to 73~nm range; these emissions dimmed 30--50\,\% during the impact events, and no new torus emissions were detected. Because no similar reduction in Io torus output was observed at longer wavelengths, the EUV luminosity reduction was very likely caused by a reduction in the population of high-energy Io torus electrons ($Ee > 17$\,eV), which excite a large fraction of the EUV emissions but a comparatively small fraction of longer wavelength emissions. Following several of the impacts, EUVE detected transient brightening events in planetary atomic helium resonance emission, HeI 58.4~nm, which was barely detected before the impacts ($I \approx 3$\,Rayleigh), although it was measured by the Voyager spacecraft during 1979 ($I = 4$\,Rayleigh). After the impact of fragment Q1 the HeI 58.4~nm brightness increased to 25--70 Rayleigh, or about 8--25 times the average brightness of Jupiter before the impacts. The brightening events indicate that the impacts lifted substantial amounts atomic helium to high altitudes in Jupiter's atmosphere, above much of the molecular hydrogen gas that normally absorbs HeI 58.4~nm photons emitted from lower altitudes. \np \bc {\bf An Interpretation of Calar Alto Ground-Based Infrared Lightcurves}\\[6pt] \bi D.P. Hamilton (Max Planck Institut f\"ur Kernphysik, Heidelberg), \\ T.M. Herbst (Max Planck Institut f\"ur Astronomie, Heidelberg),\\ H. B\"ohnhardt (Universitats-Sternwarte, M\"unchen),\\ J.L. Ortiz (Instituto de Astrofisica de Andalucia, Granada),\\ A. Richichi (Max Planck Institut f\"ur Astronomie, Heidelberg), and\\ G. Calamai (Osservatorio Astrofisico di Arcetri, Italy).\\[6pt] \ei \ec We describe 2.3\mic~and 3.1\mic~data obtained at Calar Alto's 3.5-meter and 2.2-meter telescopes during the impacts of Shoemaker-Levy 9 fragments A,E,H,L,Q1,Q2, and S with Jupiter. All of these impact events produced significant brightening of the jovian disk lasting on the order of 10-20 minutes. These ``main events'' are the brightest features seen by infrared and optical telescopes. Five of the impacts - those for fragments A,H,L,Q1, and Q2 - show fainter precursor features which begin roughly five minutes before the main events. For impacts H and L, there are additional features at still earlier times. These sharp H and L first precursors rise, peak, and begin to fade before the onset of the signals detected by Galileo's PPR instrument. Signals from Jupiter might be expected from several stages of each impact including the bolide entry into the jovian atmosphere, the rising impact shock wave and fireball, reflected sunlight and thermal emission from the ejecta plume, reimpacting ejecta, and the rotation of the glowing impact site into view. Interpretations are difficult due to the far-side location of the impact sites and the changing geometry from one impact to the next. We present our infrared lightcurves and attempt to interpret specific features in these curves in terms of physical mechanisms. \np \bc {\bf Observations of the Dynamic Response of Jupiter's Atmosphere to the Impact of Comet Shoe\-maker-Levy 9}\\[6pt] \bi J.\ Harrington, T.\ E.\ Dowling, C.\ M.\ Santori, H.\ B.\ Hammel, J.\ R.\ Mills (MIT),\\ A.\ P.\ Ingersoll (Caltech), R.\ F.\ Beebe (NMSU),\\ G.\ S.\ Orton, P.\ Chodas, D.\ Yeomans (JPL)\\[6pt] \ei \ec We present HST images of impact sites A, E, G, Q1, and R during their first planetary rotations (Hammel et al., Science, 1995). They each show one or two rings expanding from the impact site and located above the atmospheric methane ($P < 380$ mbar). Outer ring radius varies linearly with time at a velocity of 454$\pm$20 m/s. The inner ring fit gives 353$\pm$83 m/s. We interpret the rings as signatures of stratospheric inertia-gravity waves, with the outer ring speed indicating a deformation radius of $\sim$1,800 km, consistent with current estimates. The observed outer ring speed corresponds to the $\sim$400 m/s waves in the 16--69 mbar layer of our pre-impact model (Harrington et al., Nature, 1994). Tropospheric IG wave speeds in this model and that of (Ingersoll et al., GRL, 1994) are closer to 100 m/s. The latter model predicted that a water-cloud wavefront (5 bars pressure) would affect the stratosphere. However, the observed outer wave moves too fast to be driven from the troposphere; this is also likely true of the inner wave. One possibility for faster tropospheric waves in that model is a water abundance many times that of estimates based on solar composition. This work was supported by NASA. \np \bc {\bf Jeans Instability in Comet Shoemaker--Levy 9}\\[6pt] \bi Joseph M. Hahn and Terrence W. Rettig\\ University of Notre Dame\\[6pt] \ei \ec Recent $N$--body simulations of a tidally disrupted comet ({\it e.g.}, Asphaug and Benz 1994) indicate that gravitational instabilities may be responsible for the appearance of comet Shoemaker--Levy 9. These models show that if the comet catastrophically fragmented into $N\gg20$ parts, the particles can gravitationally recondense into $n$ fragments a few hours after periapse. Since $n$ depends sensitively on the parent comet's density $\rho$, catastrophic disruption of a comet provides a sensitive measure of its density. We show, via a tidal impulse model, that if tides disrupted S--L 9 into a cloud of many particles, the resulting cloud is Jeans unstable and condenses to $\sim20$ fragments about 10 hours after periapse for a comet density $\rho\sim0.6$ gm/cm$^3$. Whether these instabilities condense to compact objects or remain as extended swarms depends upon the rate at which particle collisions might damp their random motions. We also show that a varicose instability in an incompressible medium cannot account for S--L 9's twenty fragments, for this instability quickly breaks up a tidally elongated cylinder into only $n\sim{\cal O}(1\mbox{ or 2})$ fragments. These results indicate that a particle gas equation of state can be representative of catastrophically disrupted comets. \np \bc {\bf Cometary Impact Lightcurves and Optical Depth Variations of\\ the Impact Plumes}\\[6pt] \bi Hitoshi Hasegawa, Satoru Takeuchi, Takuya Yamashita, Kazu Sekiguchi,\\ and Jun-ichi Watanabe\\[6pt] \ei \ec During the impacts of comet P/Shoemaker-Levy 9, we obtained several light curves of the impacts at near-infrared wavelenghts at the Okayama Astrophysical Observatory (OAO) and the South Africa Astrophysical Observatory (SAAO). Impacts of larger fragments showed multiple flashes. The largest impact that we observed was the fragment K, and it showed triple flashes. The first faint flash and subsequent secondally flash are thought to be an entry flash of bolide phase and its expanding plume over Jovian horizon respectively. The first entry flash might be missed in most of the smaller fragments. The all of the third flash appeared 6-7 minutes after their impact times and are the brightest. We tried to investigate the lightcurves in terms of optical depth variation of the impact plume. A nucleation theory in the solar composition gas was applied to the expanding plume gas. We suggest that the secondary flash was mainly due to gas phase opacity variation and that grain formation of cometary originated silicate dusts will contribute a large amount of the brightest third flash. \np \bc {\bf Reflectivities of the Cometary Impact Sites}\\[6pt] \bi Hitoshi Hasegawa, Satoru Takeuchi, Takuya Yamashita, and Jun-ichi Watanabe\\[6pt] \ei \ec Observation of the cometary impact sites of comet P/Sheomaker-Levy 9 at near-infrared wavelengths were carried out with a near infrared imaging system OASIS at the Okayama Astrophysical Observatory. The observed wavelengths are the strong methane absorption band at 2.3 micron, intermediate methane absorption at 1.7 micron, and 2.2 micron. Theese impact sites showed as brighter clouds on the disk. The reflectivities of several impact sites were measured from these images at these different wavelengths. Center to Limb variation curves indicate that their cloud top located at the stratosphere about 1 - 2 mbar. The material of the aerosol particle is still unknown, but we suggest that magesium silicate dust nucleated in the explosion plume for the most plausible candidates of the grain. \np \bc {\bf Near Infrared Spectroscopy and Long-Term Monitoring of the SL-9 Impacts}\\[6pt] \bi T. M.Herbst (Max-Planck-Institut f\"ur Astronomie, Heidelberg)\\ D. P.Hamilton (Max-Planck-Institut f\"ur Kernphysik, Heidelberg)\\ H. B\"ohnhardt (Universit\"ats--Sternewarte, M\"unchen)\\ J. L. Ortiz-Moreno Instituto de Astrofisica de Andalucia, Granada\\[6pt] \ei \ec We present K band spectra taken during the H and L impacts and attempt to derive physical conditions in the emitting regions. Prominent spectral features due to CO and methane indicate temperatures in excess of 2000 K near maximum light. These spectral lines faded within minutes. Monitoring of the impact sites in the days, weeks, and months after the collision shows longitudinal spreading of the ejecta structures at a rate of ~10 m/s. The resulting band displayed significant inhomogeneities as late as February 1995. Although still prominent at 2.3 microns, the band has faded considerably since solar conjunction. \np \bc {\bf The Collision of Comet P/Shoemaker-Levy 9 and Jupiter}\\[6pt] \bi John J. Hillman, David A. Glenar, William C. Maguire, Gordon Chin,\\ William E. Blass$^{1}$ and Miska Le Louarn$^{2}$\\[6pt] Laboratory for Extraterrestrial Physics\\ NASA/Goddard Space Flight Center\\ Greenbelt, MD\\[6pt] \ei \ec \bi $^{1}$Department of Physics and Astronomy\\ Univ. Tennessee, Knoxville, TN\\ $^{2}$Universities Space Research Association, Seabrook, MD\\[6pt] \ei We observed the southern hemisphere of Jupiter on two nights during this impact sequence, using the Coude focus at the Kirtland Air Force Base, 1.5- meter adaptive optics telescope. Our objectives were to recover a set of scattering properties and likely vertical distributions of material at the impact site locations. Multispectral images were acquired in the methane bands at 725- and 890-nm and in their adjacent continuum using an acousto- optic tunable filter (AOTF) imaging spectrometer with a silicon CCD at the focal plane. The stratosphere near 1-mbar was simultaneously sounded by imaging in the deep 2.35-micron methane band using a NICMOS-3 camera with cooled narrow band (0.05-micron FWHM) filter. All observations were photometrically calibrated and reduced to absolute reflectivity (I/F) using close coincidence standard stars and published solar intensities. We subsequently narrowed the observed point spread function in the images by employing a modified inverse Fourier deconvolution algorithm and then renormalized to the original I/F scale. For the "quiet" atmosphere we have adopted a vertically inhomogeneous atmos- pheric model using two clouds and a high-level thin haze which was optimized to fit our observed Jupiter center-to-limb I/F variations. We then inter- leave a collision site layer with a variable top and bottom boundary, optical density, single-scattering albedo and phase function. Results on several collision sites will be presented. \np \begin{center} {\bf The Search for Historical Impact Sites on Jupiter}\\[6pt] {\it Thomas Hockey, University of Northern Iowa}\\[6pt] \end{center} A search was made through historical reports of major dark spots on Jupiter, recorded during the pre-photographic era. While many of these reports meet the sufficient condition for impact candidacy (exogenic origin cannot be ruled out), the descriptions and drawings lack the detail required to meet the necessary condition (a morphology similar to that created by the Shoemaker-Levy 9 impacts). The lack of available information about specific historical spots on Jupiter is a consequence of the perceived physical nature of these spots at the time, and the traditional purpose of jovian spot observations. \newpage \bc {\bf Direct Observations of the Comet Shoemaker-Levy 9 Fragment G Impact by Galileo UVS}\\[6pt] \bi C. W. Hord (1), W. R. Pryor (1), W. K. Tobiska (2), A. I. F. Stewart (1), K. E. Simmons (1),\\ J. J. Gebben (1), C. A. Barth (1), W. E. McClintock (1), L. W. Esposito (1),\\ R. A. West (2), S. J. Edberg (2), J. M. Ajello (2),\\ and K. L. Naviaux (2)\\[6pt] \ei \ec \bi (1) Laboratory for Atmospheric and Space Physics\\ University of Colorado\\ Boulder, CO 80303\\[6pt] (2) Jet Propulsion Laboratory\\ California Institute of Technology\\[6pt] \ei The Galileo Ultraviolet Spectrometer (UVS) team has detected the Shoemaker-Levy 9 fragment G impact on Jupiter in data recently played back from the spacecraft tape recorder. A 20\% brightening of the disc-integrated signal of Jupiter was detected at 292 nm during a swath across Jupiter that lasted $1.6$ sec and was centered at 1994-July 18 (day 199)/07:33:31 UT (all times in this paper are corrected to be the time of the event as seen from Earth). The emission brightness, when combined with simultaneous Photopolarimeter Radiometer (PPR) measurements at 945 nm, is consistent with thermal radiation at a temperature of 7800 ($+$500, $-$600) K emitted over an area of 40 ($+$60, $-$25) km$^2$. No excess signal was seen during swaths $5.33$ sec before and after the detection swath. \np \bc {\bf On Particle Acceleration by the Impact-driven Field-aligned Current System}\\[6pt] \bi W. H. Ip\\ Max-Planck-Institut fuer Aeronomie\\ D-37191 Katlenburg-Lindau, FRG\\[6pt] \ei \ec Following the scenario that a localized atmospheric wind system will be generated at the comet impact sites as a result of the energy release from atmospheric explosion (Hill and Dessler, 1995; Ip, 1995), a simple model is constructed to estimate the possible ranges of the electric current flows and the associated potential drop. The particle acceleration effect caused by a potential drop of 100 eV - keV along the magnetic field line could in turn produce the ultraviolet emissions observed by HST after the K impact. Such ionospheric dynamo mechanism might have some interesting implication on the energy budget of the Jovian thermosphere as well. \np \bc {\bf On the Ballistic Nature of the Shoemaker-Levy~9 Impact Plumes A,E, and G}\\[6pt] \bi Kandis Lea Jessup (University of Michigan, AOSS)\\ John T. Clarke (University of Michigan, SPRL)\\ Heidi B. Hammel (M.I.T.)\\[6pt] \ei \ec We present the time evolution of the plumes associated with SL9 impacts A, E, and G. Our results are based on the analysis of real time HST WF/PC2 images for each event, as well as those of the ejecta pattern imaged 1-2 hours subsequent to each event. From these images we have determined altitude above the limb and displacement in the plane parallel to the "surface" of the planet for each plume as a function of time. We have also cal- culated the ballistic trajectories necessary to reproduce each ejecta pattern, including coriolis deflection, for comparison. Thus we have reconstructed the flight of each plume, constraining the location at which the material descends through the atmosphere of Jupiter and the initial timing of each explosion event. \np \bc {\bf Comet Capture Statistics}\\[6pt] \bi D. M. Kary\\ UCSB\\[6pt] L. Dones\\ San Jose St.\\[6pt] \ei \ec Before being observed, Comet P/Shoemaker-Levy 9 had orbited Jupiter for several decades (L. Benner, W.B. McKinnon 1994, BAAS 26, 1564). We have investigated comet capture statistics through numerical simulations of test particles with orbits like those of Jupiter-family comets. We did 4-body point-mass integrations (Jupiter, Saturn, Sun, and comet), following the orbits of $\sim3\times 10^4$ bodies for $\sim10^5$ years. Over $2.7\times 10^5$ captures occured. Of the $2.1\times 10^4$ captures which make 1 or more orbits around Jupiter, $<0.2\%$ make 20+ orbits (corresponding to 50+ years) around Jupiter. Of the captures which get closer than $2.4R_J$, 4.4\% made 20+ orbits. Provided close passage is necessary for making a captured comet observable, the bias in favor of long-term capture events is significant. This work is supported by NASA Planetary Geology and Geophysics Grant \# NAGW-2061 at UCSB and by RTOP 151-01-60-09 at NASA Ames. \np \begin{center} {\bf Infrared Spectroscopy of Jupiter's Atmosphere after the A, D, and E Impacts of \mbox{Comet P/Shoemaker-Levy 9}}\\[6pt] \begin{it} Sang J. Kim\\ Department of Astronomy and Space Science\\ Kyunghee University\\ Yongin, Kyunggido, Korea\\ and\\ Department of Astronomy\\ University of Maryland\\ College Park, MD 20742, USA\\[6pt] Glenn S. Orton\\ Jet Propulsion Laboratory\\ MS 169-237\\ 2800 Oak Grove Dr.\\ Pasadena, CA 91109, USA\\[6pt] Christophe Dumas\\ Institute for Astronomy\\ University of Hawaii\\ 2680 Woodlawn Dr.\\ Honolulu, HI 96822, USA\\[6pt] \end{it} \end{center} Infrared spectra of Jupiter's atmosphere were obtained with the Infrared Spectrometer (IRS) on the 1.5-m telescope at the Cerro Tololo Inter-American Observatory (CTIO) during the first two days of the impacts of the fragments of Comet \mbox{Shoemaker-Levy 9} (1993e). We monitored 2 - 4 micron radiation from the impact areas, undisturbed areas, and auroral regions of Jupiter after the A, D, and E impacts. The strong emission of the 3 micron band of methane was detected on the A impact area 4 hours after the impact. Emissions of trihydrogen ions decreased at the A and E impact sites compared with undisturbed areas at the same latitude. The temperatures of trihydrogen ions in the southern auroral region were normal within the first several hours following the A, D, and E impacts. \newpage \begin{center} {\bf Sizes of the Comet SL9 Secondary Nuclei A and Q2 Calculated on the Basis of Physical Parameters of Light Echoes from Europa and Io}\\[6pt] \begin{it} Kleshchonok V.V., Churyumov K.I.\\ Astronomical Observatory of Kiev University, Ukraine\\[6pt] \end{it} \end{center} On the basis of high-speed photoelectric observations of Europa and Io, fireball flashes in the atmosphere of Jupiter during the impacts of fragments A and Q2 of comet SL-9 were recorded. The flash of the A fragment on July 16, with an amplitude of 0.12 mag and a duration of 0.7 sec, was recorded during observations of Europa. The flash of the Q2 fragment on July 20, with an amplitude of 0.11 mag and a duration of 1.0 sec, was recorded during observations of Io. Analogous parameters of the second flash were obtained at the Vatican Observatory [1]. The data allowed us to estimate the energy of the flashes and fragment radii. Taking into account the paper by Sekanina [2] that in light energy of fireball radiation transforms 1% from kinetic energy of secondary nucleus of comet SL-9 during its impact with the Jupiter atmosphere we will obtain the following estimate for sizes of secondary nuclei A and Q2 of SL-9: R(A)=1.42 km for $\rho$=0.3 g/cm3 (1.00 km for $\rho$=1.0 g/cm3); R(Q2)=0.65 km for $\rho$=0.3 g/cm3 (0.43 km for $\rho$=1.0 g/cm3 ). In the paper by Hammel H.B. and Nelson R.M. [3] parameters of flashes of brightness of Io that had the amplitude about 0.5 mag and that was observed July 26, 1983 are given. This observation was obtained with the 1.52-m telescope through 420 nm filter at the Palomar observatory.Though the flash on Io that was registered by Hammel and Nelson is noticeably greater then the one we registered in 1994 on Jupiter after July 26, 1983 there was not observed a somewhat visible new spot that can be compared with those spots that were formed on Jupiter after the collision of comet SL-9 with Jupiter. This fact is evidence of that that the flash of brightness of Io in 1983 was not caused by light echo from a possible fireball on Jupiter. The most probable reason for this flash to occur could be fall down on Io of 1-2 km asteroid or icy cometary nucleus. As a result of this collision from Io's surface a chain of bodies containing matter from the surface layers of Io whose composition as is known comprise Na, S2 and other elements could be exploded. Bodies exploded from the surface of Io, we think, could form a cometary train that in 1993 was detected by Shoemaker and Levy as a new comet consisting of 21 secondary nuclei.\\ References:\\ 1. G.J.Consolmagno and G.Menard. A Search for Light Echoes of A, H, and Q Events. European SL-9/Jupiter Workshop. February 13-15, 1995. Garcbing, Germany, p. 25-26.\\ 2. Sekanina Z. Disintegration phenomena expected during collision of comet SL-9 with Jupiter. Science, 262, p.382-387 (1993).\\ 3. Hammel H.B. and Nelson R.M. Bright flash on Jupiter in 1983. Nature, 1, N11, p.46 (1993). \newpage \begin{center} {\bf Near-Infrared Spectroscopy of the R Impact Site of Comet \mbox{Shoemaker-Levy 9}} \vspace{1cm} R.F. Knacke$^{1}$, S.B. Fajardo-Acosta$^{1}$, T.R. Geballe$^{2}$, \& K.S. Noll$^{3}$\\ \end{center} \vspace{1cm} \noindent $^{1}$ Penn State Erie, The Behrend College, Erie, PA 16563 \noindent $^{2}$ Joint Astronomy Center, University Park, Hilo, HI 96720 \noindent $^{3}$ Space Telescope Science Institute, Baltimore, MD 21218 We present 2.20--2.41 $\mu$m spectroscopy of the R event of Comet Shoemaker-Levy 9, spanning approximately 45 minutes prior, during, and after the impact. We model the spectra with temporally variable column abundances of mainly CH$_{4}$ and CO. The CO 2--0 bandhead is visible during and shortly after the impact event, implying temperatures $\geq$ 2000 K. The 3--1 and 4--2 CO bandheads are possibly present in some spectra, blended with CH$_{4}$ lines. Therefore some of the CO could have reached temperatures $\geq$ 3000 K. Absorption on the red side of the 2--0 bandhead by cooler ($T \approx 1000$ K) CO is also evident. \newpage \begin{center} {\large \bf CCD Spectroscopy of Jupiter's Crash Latitude\\ in 4600-10,240 \AA{} Wavelength Region\\} \medskip P.P.\,Korsun$^{1}$, Yu.V.\,Sizonenko$^{1}$,\\ S.G.\,Sergeev$^{2}$, and S.V.\,Berdyugina$^{2}$ \end{center} 1 Main Astronomical Observatory, Kyiv, Ukraine 2 Astrophysical Observatory, Nauchny, Crimea, Ukraine \bigskip \noindent The impact sites of the fragments of the Comet Shoemaker-Levy 9 in the Jovian atmosphere were observed using the 2.6-m Shajn Telescope of the Crimean Astrophysical Observatory. We obtained long-slit CCD spectra of the spots DGRS, FTVE, H, K, KUW, L, and N at the Nasmyth and coude foci. The Nasmyth spectra covered the spectral region from 4600 to 10,240 \AA{} at a resolution of 4.5 \AA. The coude spectra were obtained at the methane band (8900 \AA) and at 5893 \AA{} (Na doublet) with resolution 0.85-1.7 \AA. We investigated both the spatial structure of the impact sites along the crash latitude, and spectral peculiarities along dispersion. All the spots were seen in absorption in the observed spectral region except for the CH$_{4}$ bands at 8900 \AA{} and 10,000 \AA, where they were brighter then undisturbed Jovian surface. Some spots showed spectral peculiarities at 7200 \AA{} (CH$_{4}$) and 7900 \AA{} (NH$_{3}$) as well. We had not detected any Na variation in our coude spectra. \newpage \bc {\bf POSSIBLE 29MHz PRECURSORS ASSOCIATED WITH SOME COMET SL9/JUPITER IMPACTS FROM RATAN-600 OBSERVATIONS}\\[6pt] \bi Korzhavin A.N., Bogod V.M., Dikij V.N., Dikij D.V., Komar, N.P.\\ Special Astrophysical Observatory of the Russian Acad. Sci.,\\ Pulkovo Branch, SAO, Pulkovo, St.Petersburg, 196140, Russia\\[6pt] \ei \ec Decametric radio observations of Jupiter were made during July 16 to 22, 1994 from the North Caucasus with the RATAN-600 radio telescope of Special Astrophysical Observatory of the Russian Academy of Sciences. A special feeder sistem was designed with a purpose to form a beam (with the main mirror) of about 15 degree width in the E-W direction allowing to make an observational session of up to one hour duration. Both right-hand and left-hand polarizations were recorded at frequency 30 MHz with 1 MHz bandwidth and 10 milliseconds time resolution. A total of 20 observational sessions of 30 - 60 minutes duration have been made. Four of them encompass impact times of some comet SL9 fragments with Jupiter and are discussed in this paper. Summarizing our data, we conclude that there is a quite high probability that each comet SL9 fragment produced a precursor burst event at decametric wavelengths when passing throughout low levels of the Jovian magnetosphere. There are also some post impact burst events. If so, the unique event, the collision of comet P/Shoemaker-Levy 9 and Jupiter, gives us an unprecedented opportunity to study the structure of the low levels of the Jovian magnetosphere (the last 20,000 Km of each fragment orbit) with a spatial resolution as high as 1-2 Km, which corresponds to our 20-40 millisecond time resolution. \np \begin{center} {\bf On the spatial distribution of fragments of Comet Shoemaker-Levy near Jupiter}\\[6pt] {\it N.Ya. Kotsarenko, K.I.Churyumov, V.N. Mal'nev, and A.N. Kotsarenko\\Kiev University, Ukraine}\\[6pt] \end{center} The fragment parameters of comet Shoemaker-Levy and their spatial distribution before entering the atmosphere of Jupiter have been determined with sufficient accuracy. Special attention must be given to the geometry of the string-of-pearls chain of fragments that were arranged along straight line on approximately equal distances between large fragments. \par Evidently such spatial distribution of fragments could be a result of explosion of the comet or could be formed by fragment interaction. Moving in strong nonhomogeneous gravitational field of Jupiter fragments weakly attract and repulse each other because of elasticity of gas atmospheres that surround each fragment. From the balance of the average attraction force of proper gravitation and the repulsion force of the atmospheres in the stationary regime we obtained the correlation between an average distance $l_i$ between fragments, their masses $m_i$ and average density number $n_0$ of the gas atmosphere particles and their effective temperatures. \par It happened to be that $l_i\sim\sqrt{m_im_{i\pm1}}$ ( $m_i$ are masses of neighbour fragments). This formula may explain the observable fact that distances between light fragments are smaller than distances between bigger fragments. The time of the interaction transmission in this system is estimated. More detailed comparison of the theory with the observed results may be made if more exact density number of the gas atmosphere $n_0$ is known. \newpage \bc {\bf VLA Observations of the Effects of the Shoemaker-Levy~9 Impact on the Synchrotron Emission from the Jovian Magnetosphere}\\[6pt] \bi A. Kundu, A. W. Grossman, J. C. L. Wang \& S.M. White (Univ. of Maryland)\\ D. O. Muhleman and M. A. Gurwell (Caltech)\\[6pt] \ei \ec We observed the Jovian system with the VLA in the X-Band (3 cms) and the C-Band (6 cms) during the week of the impact. High resolution interferometric images of the linearly polarized emission from Jupiter's magnetosphere were obtained. The source of the polarized emission at these wavelengths is synchrotron emission by high energy electrons trapped in the inner magnetosphere. The intensity and morphology of the synchrotron radiation is dependent on the configuration of the Jovian magnetic field with respect to earth, the energy of the electrons, and their pitch angle relative to the magnetic field. Our maps resolve the detailed structure of the emission out to 2.5 jovian radii with a spatial resolution of 1.5 arcsecs. Snapshot images at different central meridian longitudes show a prominent region of extended emission along the magnetic equator on either side of the disk of Jupiter. Regions of diffuse emission are also observed at high magnetic latitudes, due to the relativistic electrons with small pitch angle at the equator. The flux from each of these regions was observed to increase by a factor of 1.2-2 in the post-impact maps. The position of the peaks of the emission migrated closer to the disk of Jupiter by up to 6 arcsecs. Comparison of the fluxes at the two wavelengths reveal a decrease in the spectral index of electrons with an energy of 25-35 MeV. The synchrotron emission is observed over a more extended region, both radially and (magnetic) latitudinally in the post-collision images of Jupiter's magnetosphere. This suggests an infusion of high energy electrons at large Jovian radii and possibly an inward radial diffusion of the radiating electrons. The latidudinal expansion of the emission regions may by explained by the infusion of electrons with intermediate pitch angles. The morphology of the synchrotron emission shows strong time dependent changes corresponding to the changing geometry of the magnetic field as seen from the earth. The interpretation of the change in the various components of the synchrotron radiation at different longitudes is the subject of an ongoing study. \np \bc {\bf 10 microns Observations of SL-9 Impacts with CAMIRAS at NOT}\\[6pt] \bi P.O. Lagage, Ph. Galdemard, R. Jouan, P. Masse, E. Pantin, M. Sauvage (CEA, DSM/DAPNIA/Service d'Astrophysique, CE Saclay, F-91191 Gif-sur-Yvette; e- mail Lagage@sapvxa.saclay.cea.fr); B. Mosser (IAP); G. Olofsson, M. Huldtgren (Stockholm Observatory); J.A. Belmonte, C. Regulo, T. Roca Cortes, J.M. Rodriguez Espinosa, M. Selby, L. Vidal (IAC); D. Gautier (Observatoire de Meudon); A. Ulla (NORDICA)\\[6pt] \ei \ec From July 16th to July 27th, Jupiter was imaged with CAMIRAS, the Saclay mid-IR camera, mounted on the 2.5 m Nordic Optical Telescope (LaPalma island, Spain). The 10-13 micron filter and the 0.9 arcsec PFoV (total field: 57x57 arcsec**2) were used. The weather conditions were fine. Out of the 10 impacts observed (A, E, F, H, L, P2, Q1, Q2, T, U), 5 were detected (A, E, H, L, Q1). The light curves obtained within 1 hour after the detected impacts are quite similar. They will be discussed in terms of plume rising above the limb (precursor flash about 2 min after Galileo detection), fall-back of material into the atmosphere (main IR peak about 13 min after impact), and sun-heated dust (bump about 20 min after impact and subsequent emission). The prime aim of the observations was the search for thermal fluctuations associated with seismic waves excited by the comet fragments. Direct information about the internal structure of Jupiter can be derived from the arrival times at various distances from the impact. The results of the search will be presented. \np \bc {\bf REDUCED FIVE MICRON LIGHT CURVE OF THE COMET SL-9 JUPITER R-IMPACT FEATURE FROM THE AIR FORCE MAUI OPTICAL STATION}\\[6pt] \bi J. V. Lambert, V. L. Porter\\ Rockwell Space Operations Company\\[6pt] J. L. Africano, D. L. Nishimoto, R. A. Nolan\\ Rockwell Power Systems\\[6pt] P. Kervin, R. Medrano\\ Phillips Laboratory\\[6pt] \ei \ec A 4.8 to 5.08 micron infrared light curve of the Comet Shoemaker-Levy 9 fragment R impact on Jupiter was derived from infrared imagery obtained using the Enhanced Longwave Spectrometer/Imager (ELSI) on the Phillips Laboratory 1.6-meter telescope at the Air Force Maui Optical Station (AMOS). The impact site became visible as it reached the planet's limb, eight minutes after the estimated impact time, then faded rapidly, within ten minutes. There is an indication of a precursor event at four and one half minutes after impact. The two-second temproal resolution light curve contains multiple maxima. The imagery was processed to obtain estimates of the impact feature peak intensity and diameter. Some five micron imagery of the C and F impacts was also obtained, as well as a few frames of the R impact in the 8 to 13 micron band. \np \begin{center} {\bf Jovian Decametric Radio L-bursts Associated with the Impact of Comet SL9\\ and Jupiter}\\[6pt] \begin{it} Xiao-Cong Li and Xi-Zhen Zhang\\ Beijing Astronomical Observatory\\ Chinese Academy of Sciences\\ Beijing 100080\\[6pt] \end{it} \end{center} The characters of two decametric radio L-bursts possibly associated with the impact of Comet SL-9 and the Jupiter are briefly described. Two L-bursts occurred on July 21,1994. They took place 55 minutes before and 13 minutes after the impact of the fragment S with the Jupiter respectively. These two radio L-bursts have been recorded at frequencies from 24.0MHz to 28.5 MHz by Beijing \thinspace Astronomical Observatory and China Research Institute of Radio Wave Propagation The bursts have distinct peak flux densities and durations. except the effect of emission from Io satellite, The peak flux densities are generally 7-8 times than that of a normal one, the longest duration is 266s. The burst occurred after the impact is coresponding with the brightening at infrared wavelength. Their spectral characters are different from that of a normal L-burst. The time profiles of the two bursts have opposite frequency drifts, and the profiles after low pass filtering(0.01Hz) have opposite arc curvatures(one is early and another later). The drift rate of the burst occurred before the impact is -377KH$_z$ , that of another one is +463.9KHz. However the profiles of two bursts are similar at ten frequencies. Their flux densities reached the maximum at 25 MHz. Along with the directions of frequency drift, their line profiles of curves became more simple, and their durations became shorter. The spectral characters of these two bursts mentioned above seem to show that the two bursts excited in a similar way by the impact of the fragment S with the Jupiter. This paper was supported by The National Nature Science Foundation of China and the Chinese Academy of Sciences. \newpage \title{ Three strong Jovian decametric radio bursts from impacts % } % \author{ Qi-Bin Li, Xi-Zhen Zhang, Jin-Lin Han \\ % {\small{\it Beijing Astronomical Observatory, Chinese Academy of Sciences, Beijing 100080, P.R. China}} } \maketitle \begin{abstract} Three strong decametric radio bursts ($>$20db), undoubtedly related to the impacts of fragments G, K, and W of Comet Shoemaker-Levy 1993e (SL-9) on the Jupiter, have been detected during the impact week at Xin-Xiang temporary Jovian Decametric Watch Station of Beijing Astronomical Observatory. All of them are narrow band events occurred at about 26.0 and 28.5MHz, and have a long duration of at least several minutes. Their completely different characteristics, (ie. strongest one before G impact, immediate response to K impact, and switching bursts after W impact), are shown in this report. \\[1mm] {\bf Key words:} Jupiter, P/comet/SL9 \end{abstract} \np \bc {\bf Temporal Evolution of the SL-9 Impact Features on Jupiter from CCD Imaging:\\ A Video Animation}\\[6pt] \bi Sanjay S. Limaye \& M. Lindgren\\[6pt] \ei \ec Jupiter was imaged from the solar telescope of the Swedish Royal Academy of Sciences at La Palma (Canary Islands) during the SL-9 impact week using a broadband filter several times a minute and exposures of \mbox{0.5 --2 s}. Typically more than four hundred images were acquired each night for about four and a half hour period on ten nights. With an image diameter of almost 600 pixels (0.06 arcsec per pixel), the scale of the spatial features resolved on the disk of Jupiter is about 700-1400 km, limited mostly by atmospheric seeing. These images are among the best CCD images of Jupiter obtained during the impact period from the earth. By mapping these images into sections of global latitude-longitude maps, the temporal evolution of the impact features is revealed dramatically, particularly when viewed as an animated sequence. Typically, all the spots observed on their initial appearance on the disk predominantly display an apparent drift in longitude as they move from the morning terminator to the bright limb. The magnitude and near constancy of the drift rate on successive rotations and the central meridian transit time measurements suggest that the actual drift rate is small and that parallax due to immense vertical displacement of the features is a dominant cause of the observed apparent longitude drift. By also removing the photometric function, some additional insights into the evolution of the impact features be obtained. For example, the magnitude of the minimum brightness of the core region appears to decrease with time for as many as 12 to 15 hours after the impact and then slowly rise. This might be indicative of the increasing optical thickness of the core region as viewed from the earth and then a gradual dispersal in the vertical and horizontal directions. The video animation sequence of mapped images illustrates the expanding ejecta around most spots and the distortion in the apparent shape of the plume as the impact features move across the disk, most likely due to uncompensated parallax. \np \bc {\bf Modeling of UBVRIJK${\bf'}$ Observations of P/Shoemaker-Levy 9: Implications for the Dust Size Distribution, Emission History, and Icy Composition}\\[6pt] \bi C.M. Lisse (HSTX/NASA-GSFC), M.F. A'Hearn (UMd), P.A. Esterle (UMd),\\ L.A. McFadden (UMd/UCSD), H.A. Weaver (STScI), L.M. Woodney (UMd)\\[6pt] \ei \ec Periodic comet P/Shoemaker-Levy 9 was observed in the UBVRIJK' passbands from January 1994 through its July 1994 impact with Jupiter from the Kitt Peak National Observatory (KPNO), the Cierro Tololo Interamerican Observatory (CTIO), the NASA/Infrared Telescope Facility (IRTF), and the Hubble Space Telescope (HST). Extended comae and dust tails many arc-seconds in extent were detected for some 10 of the cometary nuclei. We have taken the UBVRIJK' images and attempted to fit them using modified Finson-Probstein/Monte Carlo dynamical models. These models calculate the classical orbit of a dust particle experiencing the gravitational influence of the Sun and Jupiter and the radiation pressure of the Sun. The observed dust tail is then fit by adjusting the rate of dust emission vs time, the velocity of dust emission vs particle size (b), and the particle size (b) distribution. The models are typically poorly constrained unless observations over a large angular scale and a large time range (> 1 month) are made. We present conclusions concerning the emission history and dust particle size distribution of P/Shoemaker-Levy from the dynamical models. We have also combined the images in different passbands to create spectra of the observed dust. We have then attempted to fit the spectra using a Mie scattering code modified to allow for porous spheres, multi-component dust, and various particle size distributions. Cross-checks to the particle size distributions found by the dynamical modeling were made. We present conclusions concerning the silicate:carbon:ice composition of the observed dust in the different cometary nuclei. \np \bc {\bf Five-Color Thermal-Infrared Spectrophotometry of Selected SL9 Impact Sites}\\[6pt] \bi T.A.\ Livengood$^{1,2}$, H.U.\ K\"aufl$^3$, T.\ Kostiuk$^2$,\\ G.L.\ Bjoraker$^2$, P.N.\ Romani$^2$, B.\ Mosser$^4$, M.\ Sauvage$^5$\\[6pt] \ei \ec \bi 1 University of Maryland, College Park, MD\\ 2 NASA/Goddard Space Flight Center, Laboratory for Extraterrestrial\\ Physics, Greenbelt, MD\\ 3 European Southern Observatory, Garching bei M\"unchen, Germany\\ 4 Institut d'Astrophysique de Paris, Paris, France\\ 5 SAP CEA, Saclay, France\\[6pt] \ei Thermal-infrared imaging of Jupiter was conducted at the European Southern Observatory in the first 3 days of the SL9 impact week, and for a week after the impacts. Five of the six filters used have proven to result in useful spectrophotometric information on the impact sites, spanning the range 7.7--13.3~$\mu$m. The spectral distribution of impact-site emission is inconsistent with blackbody thermal emission. The spectra of different impact sites are also distinct, despite the presumably homogeneous atmospheric and impactor composition. Presumably, the only variables between impacts were the fragment size and mass distribution (fragment swarms versus single fragments). We will report on several impact sites and investigate the nature of differences between them. \np \begin{center} {\bf Some Results from the Ukrainian Observations of the SL9 Collision with Jupiter}\\[6pt] \begin{it} D.F. Lupishko\\ Astronomical Observatory of Kharkiv University\\ Ukraine\\[6pt] \end{it} \end{center} Within the scope of the Ukraine Program the comprehensive observations of Jupiter and its sattelites were carried out. Hundreds of distributions of brightness and polarization along the Jovian central meridian were obtained before, during and after the collision. Two splashes of Io brightness were recorded as a result of collision of comet fragments with Jupiter. These data were used to estimate an explosion energy, mass and size of fragments. The fast spectral changes (from 10 sec to 10 min) of intensity of Na, Li, Ca lines and of $CH_{4}$, $NH_{3}$ and $H_{2}$ were detected. The decrease of methane absorption at 0.89 and 1 $\mu$m occured to be the overal peculiarity of the impact sites on Jupiter. It is varied from 10-15$\%$ (medium-sized spots) to 20-50$\%$ (giant spots). The Doppler shift of some lines is evidence of very rapid movements of atmospheric matter. \newpage \bc {\bf Thermochemical and Kinetic Modeling of the SL9 Impact Debris}\\[6pt] \bi James R. Lyons\\ Caltech\\[6pt] \ei \ec Aerosols and dust particles in a variety of environments typically have imaginary refractive index k ~ 1E-3 to 1E-2. The particles are (or are thought to be) heterogeneous, consisting primarily of a weak absorber (eg. silicates,sulfates) and a small amount of a strong absorber, usually carbon soot. West et al. (1995) reported k ~ 6E-3 to 3E-2 for the SL9 impact debris observed at wavelengths from 950 to 250 nm. The relatively flat k through the visible is strongly suggestive of the presence of a soot-like compound, either as small (~ 10 nm) soot/graphite particles distributed throughtout the debris particle, or as some other species with high carbon content. The stronger absorption exhibited by the debris particles in the blue and near-uv is qualitatively well-matched by poly-HCN (West et al,1995). Thermochemical analysis of a mixture of Jovian gas at temperatures ~ 1500 to 2000 K and pressures ~ 1E-2 to 1E+2 suggests that a significant fraction of carbon is present as graphite; at higher temperatures little or no graphite is seen. However, very low quantites of PAH's and higher polyacetylenes are predicted, suggesting that in a gas of jovian composition, the kinetics may be too slow to form appreciable soot. Increasing the C/H ratio from 1E-3 (Jovian mix) to C/H ~ 1E-1 results in large quantities of PAH's and polyacetylenes at equilibrium, thus providing rapid pathways for soot formation. Such a large C/H ratio could only result from cometary material, and would only yield soot if C > O locally, as might be true for cometary crust. While abundant HCN is expected, it seems unlikely that true poly-HCN would form. However, given the lack of chemical data on HCN polymers, poly-HCN and other less complex HCN polymers cannot be ruled out. \np \bc {\bf Case Study of Enhancement of HST Images of Pre-crash SL9 and Enhancement Related Considerations}\\[6pt] \bi Stephen L. Mahan\\ Gordon Chin$^{*}$\\ William E. Blass\\ Larry Senesac\\ James Rasnake\\[6pt] Department of Physics and Astronomy \\ The University of Tennessee \\ Knoxville, TN 37996-1200 \\ \ei \ec \bi $^{*}$ Laboratory for Extraterrestrial Physics \\ Goddard Space Flight Center, Greenbelt, MD 20771\\[6pt] \ei Using the image restoration methods presented at the STScI Restoration of HST Images and Spectra II 1993 Workshop (Chin, Mahan, and Blass, Proceedings p. 49), we have enhanced HST WFPC-I and WFPC-II SL9 pre-crash images. Correlation of the enhanced images with the observed impacts is presented. Attempts to recover morphological information from the restored images will be discussed. We shall also report on work in progress including an attempt to determine the point spread function of John Hillman and David Glenar's AOTF imaging spectrometer coupled to the Kirtland Air Force Base, 1.5 meter adaptive optics telescope (cf. abstract, this conference) using enhanced HST WFPC-II images as ''ground truth''. \np \bc {\bf 3- and 5-micron spectroscopy of Jupiter at the Canada-France-Hawaii telescope during the collision of comet SL-9 } \ec \vs J.P. Maillard (IAP, France), P. Drossart, B. B\'ezard, C. de Bergh, E. Lellouch, A. Marten (Obs. Paris, France), J. Caldwell (York Univ., Canada), J.C. Hilico (Univ. Bourgogne, France), S.K. Atreya (Univ. Michigan, USA) \vs High-resolution spectra of Jupiter were obtained with the Fourier Transform Spectrometer at the Canada-France-Hawaii telescope from July 17 to July 21, 1994. They cover different spectral regions between 1.4 and 5 microns. Important modifications were observed in 3- and 5-micron spectra recorded a short time after the impacts. The 3-micron spectra observed just after impacts C and R, using a 2.5 arc-sec aperture centered on the collision sites, reveal an unusual emission that we identify as CH$_{4}$ emission originating from a very small region of the atmosphere (probably less than 100 km wide) heated to temperatures between 750 and 1500 K and located somewhere between 10$^{-5}$ and 10$^{-4}$ bar. In a spectrum recorded around 4.7 microns 4.5 hours after impact L, we detect CO emissions which are not usually present. We estimate that they are due to a local temperature enhancement of the order of 100 K near the 2-microbar level combined with a huge enhancement in the CO abundance. The spectrum also suggests a decrease of the temperature by at least 30 K between the 2- and 200-microbar levels. A more refined analysis of our observations will come from a detailed comparison of our results with the CH$_{4}$ data of Dinelli et al. (B.A.A.S., vol.26, p.1582, 1994) on impact C, and the CO data of Brooke et al. (B.A.A.S., vol.26, 1585, 1994) on impact L. Comparison with observations at other wavelengths and different impacts will also be quite useful. \newpage \begin{center} {\bf Status of the IRTF SL/9-R Seismic Wave Search}\\[6pt] \begin{it} M. Marley and C. Walter\\ New Mexico State University\\[6pt] K. Wells, D. Hunten, A. Sprague, W. Hoffmann,\\ M. Sykes, and A.Dayal\\ University of Arizona\\[6pt] L. Deutsch \\ University of Massachusetts \\[6pt] G. Fazio \\ Smithsonian Astrophysical Observatory \\[6pt] J. Hora \\ University of Hawaii \\[6pt] \end{it} \end{center} The search continues for seismic waves launched by the R impact on approximately 200 $7.8\,\rm \mu$m images of Jupiter obtained with the instrument MIRAC2 on the IRTF. We have constructed a hodogram (an image of mean pixel intensity as a function of angular distance from the impact site and time) utilizing all of the IRTF data. The azimuthal averaging substantially improves the experiment sensitivity over that reported earlier. Assuming a wave excitation efficiency of 15\%, our upper limit to the impact energy of the R event is about now $4\times10^{27}\,\rm erg$. Interestingly, this limit is comparable to that derived from observations at the NOT telescope of the L impact employing an order-of-magnitude more $10\,\rm \mu m$ images (Mosser {\it et al.} European SL/9 Meeting, 1995). The IRTF experiment thus demonstrates the power of the $7.8\,\rm \mu m$ methane band for seismological observations of Jupiter. \np \bc {\bf Galileo PPR Observations of SL9 Impact Fragments G, H, L, and Q1}\\[6pt] \bi Terry Z. Martin \& Glenn S. Orton\\ Jet Propulsion Laboratory\\[6pt] \ei \ec The Galileo spacecraft obtained a direct view of the SL9 impacts. High speed photometry by the PPR of SL9 fragment impacts G, H, and L at 945 and 678 nm shows a characteristic light curve shape. "Precursor" flashes in earthbased telescopic data imply that the initial bolide phase was not detected by the PPR nor by the Galileo instruments NIMS, UVS, and SSI. Thus, detected light arises from the fireball. The sharp change in slope of the PPR 945 nm light curves after the steep initial 2 sec rise suggests that a new opacity source developed then, due to formation of an atomic or molecular species. \np \bc {\bf Hydrogen Cyanide Polymers from the Collision of\\ Comet Shoemaker-Levy 9 with Jupiter}\\[6pt] \bi C. N. Matthews\\ Dept. of Chemistry\\ Univ. of Illinois at Chicago\\[6pt] \ei \ec Hydrogen cyanide polymers--heterogeneous solids ranging in color from yellow to orange to brown to black--may be among the organic macromolecules most readily formed within the solar system. The non-volatile black crust of comet Halley, for example, as well as the orange atmosphere of Jupiter, might consist largely of such polymers synthesized from HCN formed by photolysis of methane and ammonia. The dark brown color arising from the impacts of comet Shoemaker-Levy 9 on Jupiter could therefore be caused mainly by the presence of HCN polymers. Spectroscopic detection of these predicted macromolecules and their by-products would strengthen significantly the hypothesis that cyanide polymerization is a preferred pathway for prebiotic and extraterrestrial chemistry. \np \bc {\bf MODELING OF THE IONOSPHERIC EFFECTS OF COMET D/SHOEMAKER LEVY 9 IMPACTS WITH JUPITER}\\[6pt] \bi A. N. Maurellis and T. E. Cravens\\ University of Kansas\\[6pt] \ei \ec Theoretical modeling of the Jovian ionosphere with and without contaminant species associated with comet Shoemaker-Levy 9 (SL9) impacts is described. Introduction into the thermosphere of species associated with the impacts such as ammonia, water, and hydrogen sulfide has a dramatic effect on the ionosphere. In particular, the ionospheric electron density can be reduced by a factor of 100 for reasonable contaminant abundances and H3+ column densities display increases of about a factor of 10 or so. These ionospheric perturbations should be present over areas of Jupiter much more extensive than the visible impact sites due to strong thermospheric winds. \np \begin{center} {\bf Recent Spectroscopic Observations of the Jovian Atmosphere\\ with the Hubble Space Telescope}\\[6pt] \begin{it} M. A. McGrath (STScI), R. V. Yelle (NASA/Ames),\\ K. S. Noll (STScI), H. A. Weaver (STScI)\\[6pt] \end{it} \end{center} We present new spectroscopic observations of the Jovian atmosphere made in March and April 1995 with the Hubble Space Telescope (HST) Faint Object Spectrograph (FOS). Observations made on 3 March 1995 at the impact latitude near the central meridian using the 0.86$''$ aperture and covering the wavelength range 160--320nm show strong NH$_3$ absorption that is significantly enhanced relative to the pre-impact (14 July 1994) spectrum. There is no evidence for the CS$_2$ or S$_2$ absorption observed in the G impact site $\sim$4 hours after G impact (Noll \etal, 1995). The 3 March spectrum also shows evidence for C$_2$H$_2$ absorption, which was the only absorber clearly evident in the pre-impact spectrum (Yelle and McGrath, 1995). FOS observations on 7 April 1995 include one spectrum obtained near the limb covering the wavelength range 220--320nm, and three spectra covering the wavelength range 160--230nm which map the impact latitude in the N-S direction at $\sim$2$\degr$ latitude intervals. The limb spectrum is very similar to pre-impact spectra, showing no evidence for the bright metallic emissions seen near the limb close to the time of the S impact on 21 July 1994 (Noll \etal, 1995). The three spectra mapping the latitude of impact also show strong NH$_3$ absorption, but show little evidence for variation of the NH$_3$ with latitude. Temporal evolution of the NH$_3$ absoprtion in spectra obtained on 14 July, 18 July, 9 August, 23 August in 1994, and 3 March and 7 April 1995 will be presented.\\ References:\\ K. S. Noll \etal, 1995. {\it Science} {\bf 267}, 1307. \\ R. V. Yelle and M. A. McGrath, submitted to {\it Icarus}, February, 1995. \np \bc {\bf CASPIR Observations from Siding Spring Observatory, Australia}\\[6pt] \bi Peter J. McGregor \\ Mount Stromlo and Siding Spring Observatories \\ Institute of Advanced Studies \\ The Australian National University\\[6pt] \ei \ec Near-infrared images of the C, D, G, K, N, R, V, and W impacts were obtained with the CASPIR instrument on the ANU 2.3 m telescope at Siding Spring Observatory, Australia. A selection of images from the G and K impacts will be presented. Images at 2.34 $\mu$m provide accurate timing of the impacts. Narrow band images in the 3--4 $\mu$m region slow the development of an emission ring surrounding the impact sites, and a region of excess northern auroral emission at a similar absolute latitude to the impacts. An image at 4.78 $\mu$m taken 25 min after the K impact shows strong emission from the impact site, indicating that the K fragment penetrated deep into the atmosphere. This emission is not present in an image taken 45 min later. \np \bc {\bf THE VERTICAL STRUCTURE OF JUPITER'S CLOUD LAYER BEFORE AND AFTER THE IMPACT BY COMET SHOEMAKER-LEVY 9}\\[6pt] \bi A. V. Morozhenko, A. S. Ovsak, and P. P. Korsun\\ Main Astronomical Observatory of National Academy of Sciences of Ukraine\\ Holosiiv, Kiiv 22, 252650, Ukraine\\[6pt] \ei \ec The vertical structure of Jupiter's cloud layers before the impact (the background) and on the place of the fragment K impact for the atmospheric pressure 0.44 $\leq$ p $leq$ 8.0 bar has been determined from the analysis of observetional data on the spectral reflectivity in methane absorption bands at 619, 727 and 880 nm. For the background the maximum particle concentration (the volume scattering coefficient is $\sim 3 \times 10^{-5} cm^{-1}$ at the 1 bar level. The effective radius of cloud particles is approximately 1.3 micron for p $>$ 1.5 bar. The altitude profile of the scattering component of the effective optical depth (scattering optical depth) forms by eddy mixing of the atmosphere. The value of vertical eddy diffusive coefficient is $D = 0.5 \times 10^{5} cm^{2} s^{-1}$ for p $\sim$ 1 bar or for the scattering optical depth 1-11. Therefore the altitude stratification of particles sizes arises and effective radius decreases from 1.3 micron ( p $=$ 1 bar), to 0.45 micron (p $=$ 0.38 bar). Thus the contradiction is explaned between estimates of effective radius obtained earlier from observations of linear and circular polarization of the planet's light and especially from the spectral dependence of the scattering optical depth. After the fragment K impact, scattering coefficient decreased almost twice for p $\sim$ 1 bar and increased slightly for p $<$ 1 bar. The value of D increased up to $10^{5} cm^{2} s^{-1}$. On the level with p $=$ 0.44 bar we have scattering optical depth 0.43. If sharp increase of D for p $<$ 0.44 bar is not assumed the appearance of the aerosol in higher layers of the stratosphere (the pressure up to several mbars) cannot be accounted by rising cloud particles. Thus, the hypothesis of its origin from the comet is very probable. The research described in this publication was made possible in part by Grant N U4R000 from the International Science Foundation. \np \begin{center} {\bf Jovian Photochemistry Following the SL9 Impacts}\\[6pt] \begin{it} J. I. Moses (LPI), M. Allen (Caltech/JPL), and G. R. Gladstone (SWRI)\\[6pt] \end{it} \end{center} \medskip The collision of SL9 with Jupiter caused many new molecular species to be injected into the Jovian stratosphere. We use a one-dimensional photochemical model to follow the evolution of the impact-derived species. Sulfur photochemistry dominates the initial evolution, but the longer-lived nitrogen and oxygen compounds also participate in the stratospheric photochemistry. We discuss the important photochemical processes operating on the impact-derived species, identify the short- and long-term reservoirs of the different elements, compare our predictions concerning the temporal variation of the major compounds with observations, and discuss the implications for aerosol formation and long-term observations. \newpage \bc {\bf Dynamic spectroscopy of Europa before the A-impact}\\[6pt] \bi \framebox{H.K.Nazarchuk} and L.M.Shulman\\ Main Astronomical Observatory of the National Academy of Sciences\\ Kyiv-22, 252650, Ukraine; e-mail: shulman@mao.gluk.apc.org\\[6pt] \ei \ec \begin{sloppypar} The spectral monitoring of Europa has been carried out on July 16, UT 19:16---20:02. The 1024-channel TV scanner at the 6-meter telescope (Special Astrophysical Observatory of Russian Academy of Sciences) was used. The result of the observation is the record of the numbers of the spectral channel where one-electron event took place each 32 msec. The spectral range covered in one exposure is $\sim1000$\AA\ approximately centered onto H--$\beta$ line: 4400---5300\AA. Each spectrum has been flatfield corrected and recalculated to the wave lengths scale using the spectrum of a Ne+Ar+He lamp. So we have got $\sim1000$ monochromatic ($\Delta\lambda\approx 1$\AA) light curves for the above mentioned time period with a time resolution at \mbox{$\sim20$ s.} This data can be considered like 128 sequential spectra as well. There were no predicted impact during this time interval but the spectra differ from the plain reflected Solar radiation slightly changed by the albedo of Europa. Besides the Solar Fraunhofer lines (the H$-\beta$ is the strongest) there are many weak and strong non stationary emission peaks. Among them a strange peak is detected at 4518\AA\ (the most probably S$^+$). It is localized in the UT 19:46--19:50 time interval when the intensity of the 4518\AA\ emission was enhanced by the factor $\sim 2$. It seems that H--$\beta$ emission in the pre-impact spectrum is present too. At least there is a feature at 4861\AA\ which is either H$-\beta$ or something else. Other possible identifications are: O$^+$(4860.93), N$^+$(4860.35), Fe(4859.75), Ca(4859.31). All these lines may occur in a high temperature meteor flush. Moreover, these lines may be present in the spectrum together as well as the H$-\beta$. Unfortunately, our spectral resolution is not good enough for a reliable choice. This emission arose two times: firstly at UT 19:28--19:30, and then simultaneously with the 4815\AA\ emission. A group of emissions is seen in the range 4920--4965\AA. They probably belong to atoms (Fe, Ni, Na, Ca, Mg, Si), ions (S$^+$, O$^+$, C$^+$, Ba$^+$, N$_2^+$), and molecules (CN, O$_2$, OH, Na$_2$, H$_2$, S$_2$). The spectrum of Europa seems to have features of a high temperature meteor spectrum. The total contribution of the emissions to the integral brightness of Europa was rather small but there was detectable spectral variations in some narrow spectral bands. It is probable that two impacts of small undetectable fragments took place at UT 19:30 and UT 19:48. It seems that a continuous meteor shower began approximately one hour before the A-impact. \end{sloppypar} \np \noindent\centerline {\bf Carbon monoxide in Jupiter's stratosphere after the impact of SL9} \bigskip \noindent {\it K. S. Noll, D. Gilmore (STScI), R. F. Knacke, M. Womack, S. Fajardo (Penn State, Behrend), C. Griffith (NAU), \& G. Orton (JPL)} \medskip Two lines of the CO 1-0 fundamental band were observed in Jupiter's spectrum before and after the impacts of comet SL9 with the CSHELL infrared spectrometer at the NASA Infrared Telescope Facility on Mauna Kea. On the nights of August 1 and 2 (UT) the 30 arcsec slit of CSHELL was placed parallel to latitude bands near the impact sites at approximately 45 degrees South and at a corresponding latitude in the Northern hemisphere. On the night of August 1 we see no difference between CO lines at the two latitudes. On the subsequent night, howver, we observe a distinct decrease in the central depth of the CO R5 and R7 lines. The observations were obtained 24 hours after the previous night's, so they sample a different range of longitudes. On August 2 our slit includes the fragment L impact site where strong CO emission was observed immediately after impact (Brooke et al.~1994 BAAS 26, abstract 03.07). An explanation consistent with our observations is that weak emission features persist and fill in the center of the CO absorption line. We will compare model spectra to the observed CO line profiles in an attempt to constrain the abundance of stratospheric CO observed with this data. This is of particular importance since it appears that CO is the primary oxygen-bearing molecule produced by the impacts (Lellouch et al.~Nature 373, 592., Bjoraker private communication), though the low HST upper limit on CO (Noll et al.~Science 267,1307.) suggests that uncertainties in the CO vertical profile remain. \np \begin{center} {\bf Jupiter's 21cm Continuum Emission caused by the Collision of Comet \mbox{Shoemaker-Levy 9}}\\[6pt] \begin{it} C. A. Olano, J.C. Testori and F.R. Colomb\\ Instituto Argentino de Radioastronomia\\ C.C.5, 1894 Villa Elisa, Argentina\\[6pt] \end{it} \end{center} From July 13 to August 21 we have observed Jupiter at 1420 MHz using one of the IAR 30-m single dish radiotelescopes. After the impact of fragment G, we detected a rapid increase of the 21cm-continuum flux, which reached the maximum (around 20% of Jupiter's flux) at the end of the impact period and then decayed within 30-60 days. The nature of this radiation is clearly synchrotron, originated probably by a new population of relativistic electrons ( 1.E28 -1.E29) injected into the Jovian magnetosphere. The energy released by the explosions under the form of relativistic electrons is of 1.E22-1.E23 erg. The decay time of the flux density, when interpreted as due to synchrotron losses, implies that the relativistic electrons were subject to a mean magnetic field of 3-5 G. However, non-synchrotron losses can better account for the magnitude of the losses required by the data. \newpage \begin{center} \Large {\bf Cloud perturbations as a result of the SL9 impacts} \end{center} \normalsize \begin{center} J.L. Ortiz$^*$, G. Orton, K. Baines, P. Yanamandra-Fisher, J. Friedson. \\ Jet Propulsion Laboratory, Pasadena, CA 91106\\ T.H. Herbst\\ Max Planck Institute f\"ur Astronomie, Heidelberg, Germany\\ D.P. Hamilton\\ Max Planck Institute f\"ur Astronomie, Heidelberg, Germany\\ H. B\"onhardt\\ Universitaets-Sternwarte, M\"unchen, Germany\\ \vskip 0.5truecm *also at the Instituto de Astrofisica de Andalucia, CSIC, Spain\\ ortiz@uli.jpl.nasa.gov ~ ortiz@iaa.es \\ \end{center} \vskip 0.5truecm The normal Jovian vertical structure was affected by the formation of a very dark haze at visible/uv wavelengths, mostly at stratospheric and upper tropospheric levels, but the perturbations at deeper levels are still uncertain. We present the first efforts to address this topic, by analyzing some imaging and spectroscopic results from Calar Alto in the range 1 to 2.5 $\mu$m on several impact areas along with IRTF mid-IR images for the same impact sites. Changes in molecular equivalent widths are investigated in the near IR as well as changes in cloud opacity for longer wavelengths. \np \bc {\bf Spatial Variation and Time Dependence of the Temperature Structure of Impact Sites}\\[6pt] \bi Glenn Orton\\ Jet Propulsion Laboratory\\ California Institute of Technology\\[6pt] Joseph Spitale\\ California Institute of Technology\\[6pt] James Friedson, Padma Yanamandra-Fisher, Kevin Baines\\ Jet Propulsion Laboratory\\ California Institute of Technology\\[6pt] William Hoffmann, Aditya Dayal\\ Steward Observatory\\ University of Arizona\\[6pt] Lynne Deutsch\\ Five-College Astronomy Department\\ University of Massachusetts\\[6pt] Joseph Hora\\ Institute for Astronomy\\ University of Hawaii\\[6pt] \ei \ec The NASA Infrared Telescope Facility comet crash program included an investigation of temperature structure at the impact sites. This experiment used the MIRAC2 mid-infrared array camera to image Jupiter at several wavelegnths where thermal emission was dominated by well mixed constituents: CH$_4$ at 7.8 $\mu$m to sense stratospheric temperatures near 8 mbar and H$_2$ at 13.0, 17.8, 20.2 and 20.8 $\mu$m to sense tropospheric temperatures between 150 and 400 mbar. We present temperature sounding results from absolutely calibrated observations which show the vertical variability of temperature as a function of time, concentrating specifically on the region near the K impact site. \np \bc {\bf HST FAINT OBJECT CAMERA UV OBSERVATIONS OF THE SHOEMAKER- LEVY 9 IMPACT SITES AND OF THEIR TEMPORAL EVOLUTION}\\[6pt] \bi R. Prang\'e \& C. Emerich (IAS/CNRS, Orsay, France)\\ D. Rego (IAS, Orsay, France and U. Michigan, USA)\\ F. Paresce (STScI, Baltimore)\\[6pt] \ei \ec Images of Jupiter have been taken in the UV with the Hubble Space Telescope Faint Object Camera (FOC) from July 13, 1994, before the beginning of the comet fragment infalls, to August 9, 1994, more than two weeks after the end of the event. The camera was used with FUV filters centered on the H$_2$ bands, collisionally excited in the high latitude aurorae, around 1500 \AA. The solar flux reflected by the atmosphere of Jupiter was also transmitted in the long wavelength wing of the transmission function. When folded with a Jovian reflected spectrum, the FOC transmitted flux peaks near 2000 \AA $ $, and covers the 1700 to 4000 \AA $ $ range. Therefore, the altitude range studied is higher than in visible images. The core of fresh impact sites is darker and more extended than the streak seen in visible images, and it is surrounded by an extended area (several arcsec), also larger and darker than the visible plumes. They are very similar to features observed with WFPC2 in the FUV, although less dark on average. This is consistent with the difference in altitude range sampled, and can be used for a comprehensive diagnostic of the plume material. Two images, taken on August 9, on both sides of Jupiter, show the long term evolution of the UV absorbing material in the upper stratosphere/thermosphere. The evolution is very different depending on the fragments, some of the plumes (as A) have almost disappeared whereas others (the major ones) are still very dark (up to 70\% absorption). In addition to longitudinal drift of the material in the stratosphere creating a belt-like feature, we identify a strong latitudinal diffusion with significant absorption from the auroral zone up to the edge of the FOC frame ($\simeq$ 20-25 $^circ$). Finally transient and/or meridional winds in the upper stratosphere are inferred from the observation of several structures drifting north of the impact region. This also is consistent with results obtained from FUV WFPC2 observations. \newpage \bc {\bf MAGNETIC MAPPING AND INTERPRETATION OF AURORAL SIGNATURES OF COMET SL9 IN THE JOVIAN MAGNETOSPHERE}\\[6pt] \bi R. Prang\'e (IAS, Orsay, France)\\ I. Engle (Naval Academy, Annapolis, USA)\\ M. Dunlop \& M.K. Dougherty (Imperial College, London, UK)\\ S. Maurice (ESTEC, Nordjwick, Netherlands)\\ W. H. Ip (MPI, Lindau, Germany)\\ J.T. Clarke \& G.E. Ballester (U. Michigan, USA)\\[6pt] \ei \ec Before impacting the dense atmosphere of Jupiter, the fragments of comet Shoemaker- Levy 9 spent a few days flying across its magnetosphere (several millions of km across). Electrodynamic interaction with the ambient plasma induced several unique phenomena detected in the UV, X ray and radio wavelength ranges. Among them, the detection of an unusual 'blinking' UV bright spot in Hubble Space Telescope images of the southern polar cap on July 20, just before P2 collision, might be attributed to auroral type processes triggered by the charged environment of the comet fragments, as described in some prediction models. A detailed modeling of the time varying morphology of the magnetic field lines enables us to compare the location of this spot with the magnetic footprint of the fragments still in the magnetosphere, and to determine the characteristics of the corresponding field line. We show that fragment Q is a good candidate, and we discuss whether the data can allow us to distinguish between the various fragments. We establish also that Q was on an open magnetic field line at the time of the observations, in agreement with the lack of observable conjugate emission from the north, although the most distant fragments may be on closed field lines. We study the deformation of the instantaneous Q magnetic field line in the hours following the UV observations, to investigate a later set of images and any possibility of relationship between this UV event and a close-in-time X ray emission from the northern hemisphere. We find that the field line passing through Q closed during two periods before the fragment impacted the atmosphere, the first one corresponding to the north X ray burst and to the second set of UV images. Under the assumption that this auroral emission is indeed a signature of the interaction of the coma of fragment Q with the magnetosphere, and that this interaction is triggered by a mechanism alike the one predicted in Ip and Prang\'e (1994) which involves field-aligned currents, we propose an explanation of the modulation of the spot brightness. \np \begin{center} {\bf On the Disappearance of the Dark Band in the Jovian Southern Hemisphere before the SL9 Impacts on the Planet}\\[6pt] \begin{it} PROKOF'EVA V.V.\\ Crimean Astrophysical Observatory\\[6pt] TARASHCHUK V.P., CHURYUMOV K.I.\\ Astronomical Observatory of Kiev University\\[6pt] \end{it} \end{center} It is known that Jupiter disc is rich in numerous details. Some of them change their contours appear and disappear within small time intervals. Other details, though they can suffer several changes, remain for month, years, centuries. They all are purely atmospheric formation because Jupiter does not have hard surface. As usual during falldown of fragments of comet Shoemaker-Levi 9 on Jupiter dark bands and light zones between them were observed. However blurring and later disappearance of the dark band in the southern hemisphere were observed. This phenomena occurred before fall down of 21 secondary nuclei, i.e. it took place before July 16 1995. After their fall down on to the visible surface of the planet dark formation, on which the spectrograph diaphragm have been guided. The principal components of the Jupiter atmosphere are hydrogen H2, helium He, methane CH4, in the gaseous state and ammonium NH3 in form of aerosol of the cloudy sheet, comprising small crystals as well as product of their dissociation as the result of photochemistry processes (C2H2 - acetylene, N2H4 - hydrazine et al.) yield the most powerful absorption bands in the visible range of the spectrum: 619, 725 nm - methane, 644.1 , 790 nm - ammonium). Sharp contours of the dark features are connected with methane, while NH3 yields more light clouds located higher and having lower temperature. Intensities of bands of methane and ammonium is dependent not only from their abundance but to a greater extent from the physical conditions in the atmosphere. Possible mechanism of the disappearance of the dark band in the Jupiter south hemisphere is discussed. \newpage \begin{center} {\bf Pre-impact Images of Comet \mbox{P/Shoemaker-Levy 9} from Las Campanas}\\[6pt] \begin{it} David L. Rabinowitz\\ Carnegie Institution of Washington, Department of Terrestrial Magnetism\\ 5241 Broad Branch Rd, NW, Washington, DC 20015\\[6pt] \end{it} \end{center} On the night of 1994 July 16 (~04:00 UT), visible light images of nuclei E, G, L, P2 (8a and 8b) , Q1, Q2, R, S, and W of comet P/Shoemaker-Levy 9 were obtained using a CCD and coronagraph at 100$"$ Dupont Telescope of Carnegie Observatories (Las Campanas, Chile). The coronagraph was built by Steve Larson (University of Arizona) as part of the Comet Impact Network Experiment [1, 2]. Each of nuclei E, G, L, Q(1,2), and W show trails of material extending towards Jupiter. Similar trails appear in Hubble Space Telescope images of the "P-Q complex" on July 20 UT, but not on July 11 UT and prior images. Because these trails extend asymmetrically from the nuclei, it is unlikely that Jovian tidal forces can explain their appearance. Other forces, such as Lorentz drag in the the Jovian magnetic field, may be responsible.\\ [1] S. Larson et al., 1994, The Comet Impact Network Experiment, BAAS 26.\\ [2] J. Scotti et al., 1994, Preliminary Results from The Comet Impact Network Experiment, BAAS 26. \np \bc {\bf Deep Coma Imaging of Comet Shoemaker-Levy 9 to Characterize Dust Outflow Velocities and Grain Sizes}\\[6pt] \bi T. W. Rettig, J. Hahn, \& G. Sobczak\\ Univ. Notre Dame\\[6pt] M. J. Mumma\\ NASA/Goddard\\[6pt] \ei \ec The comae resulting from the approximately 20 fragments of Comet Shoemaker-Levy 9 present a unique opportunity to characterize the ejected cometary dust grains that were once buried deep within the parent progenitor. We present an analysis of the spatial brightness profiles of P/S-L 9's inner comae extracted from Hubble Space Telescope images obtained from January through July 1994. These profiles reveal that most of the S-L 9 fragments exhibit the usual r$^{-1}$ spatial dependence in their inner r $\leq 1''$ comae in observations where jovian tides are unimportant. Beyond this distance, the comae lose their circular appearance as radiation pressure drives the dust tailward. This distance is related to two unknown properties of comet dust grains: the grain size and outflow velocity. But when the comet fragments are within about 100RJ of Jupiter, where RJ is one Jupiter radius, jovian tides become the dominant perturbation acting on the comae. However, the projected distance beyond which tides distort the comae are related only to a single unknown, the dust outflow velocity. Thus, by measuring the distance beyond which the comae are initially distorted by radiation pressure, and in later observations by tides, we are able to extract an estimate of the characteristic dust grain size, which is of order 10 to 100 microns, and its outflow velocity ~3 meters/sec. In comparison to gas driven cometary outflows measured in other comets, the emitted dust grains leaving the P/S-L 9 fragments are unusually large with considerably lower velocities. In addition to the dust sizes and velocities, the surface brightness profiles will be used to extract the central brightness excesses which are a measure of the reflecting area in the inner comae regions. We will also present the temporal magnitude variations of the inner comae regions. These observations are being used in conjunction with tidally distorted Monte Carlo models to place constraints on the dust outflow velocities and dust production rates. \np \bc {\bf Evolution and Drift of the Visible Impact Scars}\\[6pt] \bi John Rogers\\ British Astronomical Association\\[6pt] \ei \ec Most of the visible SL9 impact sites lasted more than a month, and their average rotation period was very close to that of the S.S.S. Temperate Current or System III. However, there was evidence for diverse local motions. At first, the black core regions had an average System III drift of +6 deg/month (+/- 5, s.d.) (omitting the multiple impact sites K/W and D/G/S). But the leading edges, peripheral clouds, and whole sites later, moved faster: -10 deg/month (+/- 12, s.d.), which is faster than the underlying cloud-top currents. By mid-September the sites had merged into an uneven new belt. In early 1995, this belt was still present but fading. \np \bc {\bf Normal Patterns of Dark Spots in Jupiter's Atmosphere}\\[6pt] \bi John Rogers and Michael Foulkes\\ British Astronomical Association\\[6pt] \ei \ec The SL9 impact scars were unprecedented in the experience of visual observers of Jupiter. All available observations of Jupiter have been surveyed (J.R., The Giant Planet Jupiter, CUP, 1995). The record is complete from 1878 onwards. Almost all dark spots are of recognisable types in fixed latitudes moving on permanent currents. There are no outstanding records of large black sudden-onset spots like impact sites G or L. Therefore the frequency of such impacts (allowing for unoservability during solar conjunction) is less than one per 70 years. \np \bc {\bf Atomic Line Emissions in the Impacts of Comet SL-9 into Jupiter}\\[6pt] \bi M. Roos-Serote, A. Barucci, J. Crovisier, P. Drossart,\\ M. Fulchignoni, L. Lecacheux and F. Roques\\[6pt] Observatoire de Paris-Meudon\\[6pt] \ei \ec High-resolution spectroscopy of Jupiter was performed during and after the impacts of comet SL-9 at the Pic du Midi 2-m telescope. Spectra with a resolving power of 36,000 between 564 and 875 nm were recorded with the MUSICOS (MUlti SIte COntinuous Spectroscopy) spectrograph. Transient emissions of atomic lines following impacts L and Q1 were detected: sodium (589 nm doublet), iron (multiplets at 804, 636 and 550 nm), calcium (657 nm intersystem line and 616 nm triplet), lithium (671 nm doublet), potassium (766 nm line) as well as the hydrogen H alpha line. These lines were detected about 15 min after the impacts and were no longer visible one hour after. The excitation process for these atomic emissions is not yet understood in every detail. The resonant fluorescence mechanism can neither account for the observed intensities nor for the presence of the Ca intersystem line. Collisional excitation is not efficient at the high altitudes reached by the plumes. The falling back of the plumes at a velocity of 10 km/s on Jupiter might explain the transient emission. Electronic recombination processes and chemical reactions might also play a role. The alkali and metals observed are not usually present in Jupiter's upper atmosphere and should come from the refractory compounds of the comet nucleus. Correct modelling of the excitation processes of the emission lines will allow the determination of the abundances of these species in the comet. \np \bc {\bf DISRUPTION OF SL9 BY VOLATILES RELEASED BY TIDAL HEATING}\\[6pt] \bi T.V. Ruzmaikina\\ Lunar and Planetary Laboratory\\ University of Arizona, Tucson 85721\\[6pt] \ei \ec The comet Shoemaker-Levy 9, revealed in March of 1993 as a string-of-pearls of 21 major fragments, has been destroyed when it passed Jupiter within Roche limit, at the distance about 1.6 of the planet's radius in 1992. In this paper we suggest an idea that the comet might had been disrupted not by the tidal force itself, but by the pressure of volatiles released due to the tidal heating. We consider the comet as a conglomeration of blocks divided by narrow "fracture" zones, and assume that the tidal force initiated the sliding of parts of the comet along one (or few) zones. Then the heat released in a narrow shear layer between the blocks could be sufficient for the evaporation of highly volatile elements and their pressure could disrupt the comet. The momentum transferred to the pieces of the comet is large enough to provide them velocities exceeding escape speed from the surface of the comet and hence prevent their coalescence, provided that the comet radius was $< 10$ km. We speculate that the shear induced release of volatiles could also cause disruption of the comet fragments in the upper layers of Jovian atmosphere, and thus explain the shallow penetration of the fragments without putting a strong restriction on their sizes. \np \bc {\bf MORPHOLOGY AND MOTIONS OF THE SL9 IMPACT CLOUDS\\ (JULY 1994-APRIL 1995)}\\[6pt] \bi A. Sanchez-Lavega (1), J. Lecacheux (2), F. Colas (3), J. M. Gomez (4), P. Laques (5), I. Miyazaki (6), and D.C. Parker(7)\\[6pt] \ei \ec \bi (1) Dpto. Fisica AplicadaI, Universidad Pais Vasco, Bilbao, Spain.\\ (2) DESPA, Obs. Paris-Meudon, France.\\ (3) Bureau des Longitudes, Paris, France.\\ (4) Grup d'Estudis Astronomics, Barcelona, Spain.\\ (5) Observatoire Pic-du-Midi, Bagneres-de-Bigorre, France.\\ (6) Oriental Astronomical Association, Okinawa, Japan.\\ (7) Association Lunar Planetary Observers, Florida, USA.\\[6pt] \ei A large number of CCD images of the SL9 impact clouds in the wavelength range 600-900 nm, taken at Pic-du-Midi Observatory in France from July 1994 to April 1995, has allowed us to study the morphological changes and motions of the impact clouds. Our measurements show the existence of at least three different kind of motions (July-August 1994): (1) Eastward expansion during the first two days of the largest impact regions (K, L, G) with velocities in the range from 36 to 60 m/s; (2) Clouds that acted probably as passive tracers of the stratospheric flow (velocities in the range -15 to 20 m/s); (3) Local motions of the cloud elements with meridional components, sometimes related to the interaction with anticyclonic ovals in nearby latitudes (velocities of about 20 m/s). The average zonal velocity relative to System III of the cores of impacts E, A, C, W, K, L, G, R, Q1 and H was (up to August 18) -1.7 m/s with an average jovicentric latitude of -43.8 deg. Since mid-August and up to early October 1994, the preferentially zonal spreading of the clouds formed a nearly complete belt at latitude -44.6 deg together with scattered clouds alongside parallels -55.0 and -36.2 deg. Post-solar conjunction observations between January and April 1995, show the permanence of the heterogeneous dark belt at -44 deg which contains numerous local condensations (size 3000-10000 km) dispersed along the whole latitude circle. Other synoptic clouds, probably pertaining to the SL9 impact, were detected at -54 deg during this period. \np \bc {\bf Comet Shoemaker-Levy 9 in Historical Context:\\ The Record of Split Comets on the Galilean Satellites}\\[6pt] \bi Paul M. Schenk (LPI, Houston, TX), Erik Asphaug (NASA ARC, Moffett Field, CA), William B. McKinnon (Wash. U., St. Louis, MO), H.J. Melosh (LPL, U. of Ariz., Tucson, AZ), and Paul Weissman (JPL, Pasadena, CA)\\[6pt] \ei \ec Shortly after discovery of comet Shoemaker-Levy 9 in 1993, Melosh and Schenk concluded that crater chains on the Galilean satellites Callisto and Ganymede were the result of the impact of past split comets. We investigate the morphology of crater chains, focusing on three key problems: \begin{itemize} \item What are the gross physical properties (e.g., mass, radii) of Jupiter-family comets? \item What are the characteristics of individual fragments at the time of impact? \item What is the nature of the breakup process: can we distinguish between 'rubble piles,' 'solid' snowballs and other breakup models? \end{itemize} We compare these properties with those of Shoemaker-Levy 9, providing a historical context in which to evaluate that event. \np \bc {\bf COLLISION OF COMET \mbox{SHOEMAKER-LEVY 9} WITH JUPITER: IMPACT STUDY OF TWO FRAGMENTS FROM TIMING OF PRECURSOR EVENTS}\\[6pt] \bi Zdenek Sekanina\\ Jet Propulsion Laboratory, California Institute of Technology\\ Pasadena, California 91109, U.S.A.\\[6pt] \ei \ec The impacts of fragments K and R of comet Shoemaker-Levy 9 are investigated with the aims to interpret the timing of the observed precursors to the main thermal emission event and to correlate the results of ground-based infrared observations with a variety of observations made onboard the Galileo space- craft. Analysis of the phenomena associated with the impact and explosion of fragment K shows that there is no discrepancy in the timing of the Earth- and Galileo-based observations and that the time of \mbox{53 $\pm$ 3} seconds between the emission peak of Precursor 1 and the onset of Precursor 2 can be interpreted as the interval between the impactor's disappearance behind the Jovian limb and the first appearance of the ejecta's plume over the limb following the explosion of the impactor's residual mass, as viewed by terrestrial observers. It is concluded that the impactor exploded at an altitude of 45 to 50 km above the pressure level of 1 bar and that the residual mass involved in the explo- sion, approximately 6 to 7 million tons and about 400 meters across, repre- sented only a fraction of 1 percent of the fragment's preatmospheric mass. The explosion is calculated to have taken place under a dynamic pressure of several hundred bars and the dissipated energy is found to have been on the order of \mbox{10$^{26}$ erg}. The results for fragment R show it to be smaller and less massive than fragment K, exploding slightly higher in the Jovian strato- sphere, 50-60 km above 1 bar. The preferred solutions suggest that the rate of ablation of these impactors was comparable with, or somewhat higher than, that of category IIIb fireballs in the Earth's atmosphere. These fireballs represent a population of objects consisting of "soft" cometary material, whose bulk density is typically \mbox{0.2 g/cm$^{3}$}. Preliminary evidence from other observations of the various fragments appears to be consistent with the pres- ent conclusions. All plume-expansion models based on penetrations below the clouds are incorrect and need major revisions. The successful prediction of explosion altitudes for the \mbox{Shoemaker-Levy 9} fragments, based on the slightly modified fundamental equations of the classical theory of meteor physics and on ablation rates derived from data on relevant terrestrial fireballs, is a tribute to the meteor theory and demonstrates the versatility of its tech- niques in applications. \np \bc {\bf SAAO K-band Imaging Observations of the Collision of\\ Comet \mbox{P/Shoemaker-Levy 9} and Jupiter}\\[6pt] \bi Kazuhiro Sekiguchi (NAO-Japan \& SAAO), Ian S Glass (SAAO),\\ and Satoru Takeuchi (Kyusyu Univ.)\\[6pt] \ei \ec We present results of K-band imaging observations of the collision of Comet \mbox{P/Shoemaker Levy 9} obtained using the SAAO/U-Tokyo/NAO-Japan PtSi IR camera on the 75-cm telescope at the SAAO Sutherland. Time resolved (30 sec and 10 sec interval) observations of the impacts by the fragments, A,E,H,P2,Q1,Q2,S and T were analyzed and K-band light curves of the each impact event have been constructed. \np \bc {\bf Interaction between the magnetospheres of comet SL9 and Jupiter}\\[6pt] \bi A. S. Sharma, G. M. Milikh and A. S. Lipatov\\ Department of Astronomy\\ University of Maryland\\ College Park, Maryland\\[6pt] \ei \ec The plasma in the cometary magnetosphere formed by the mass loading of the solar wind by the cometary ions is tenuous and has low energies at 5 AU. Simulations using hybrid (particle ions and fluid electrons) plasma simulation codes have given plasma density of 2--3 cm-3 and electron temperature of a few eV in the cometary bow shock region. The interaction of the Jovian and cometary magnetospheres, simulated with these codes, yields local enhancements of the magnetic field and plasma density by a factor of 4 -- 5 and the electron temperature by 2-- 3. Enhancement in the intensities of the ion emissions in this region was predicted at the SL9 - Jupiter encounter and the HST/FOS observations have shown a strong MgII 280 nm emission at 53 RJ from Jupiter. The detailed modeling of the emissions and its implications to the magnetospheres at the interaction will be presented. \np \bc {\bf Global Maps and Drift Rates for Jovian Features}\\[6pt] \bi Simon, A. A., Beebe, R. F., \& Chanover, N. J.\\ New Mexico State University\\[6pt] \ei \ec Using Hubble Space Telescope Cycle 4 data obtained on February 13, 1995 with WFPC2, a maximum resolution global map of Jupiter has been constructed at a wavelength of 410 nm. This map can be compared to a similar map produced from images taken after the Comet P/Shoemaker-Levy 9 impacts on July 23, 1994. Standard features have been tagged on the February 13th map, and their drift rates computed. This is important in studying cloud morphologies and transient features on Jupiter. In addition, interacting features have been tagged on the impact map and their circulation rates determined. \np \bc {\bf Radio Observations of Jupiter from HartRAO}\\[6pt] \bi D.P. Smits \& G.D. Nicolson\\[6pt] \ei \ec Monitoring of Jupiter's microwave emission at wavelengths of 18, 13, 6 and 3.6 cm commenced at the Hartebeesthoek Radio Astronomy Observatory (HartRAO) a few weeks prior to the collision of the fragments of comet Shoemaker-Levy 9 into the planet, continued daily during the week of impacts and irregularly thereafter. Short-timescale 6 cm and 3.6 cm data collected during the times of 2 impacts show no observable changes. The horizon-to-horizon runs recorded during the week of impacts show a gradual flux increase. The largest increases occurred at 18 and 13 cm suggesting that the synchrotron emission has increased. Monitoring of the fluxes after the collisions shows that they have remained in their high state. The analyzed data will be presented together with recent radio data (1995) from Jupiter collected at HartRAO. \np \bc {\bf Near-IR Images and Spectra of the Impact Sites from Cerro Tololo}\\[6pt] \bi John R. Spencer (Lowell Observatory), Darren L. DePoy (Ohio State University),\\ Glenn S. Orton (JPL), Christophe Dumas (University of Hawaii),\\ Sang J. Kim (University of Maryland)\\[6pt] \ei \ec We used the 1 - 2.5 micron Ohio State Infrared Imager Spectrometer (OSIRIS) to observe the Shoemaker-Levy 9 impacts from the CTIO 4-meter telescope in Chile. We obtained 1.58, 1.7, and 2.3 micron images and 1-2.5 micron cross-dispersed R=500 spectra of the impact sites during the following times in July (given in fractional days): 16.95--17.15; 17.93--18.15; 19.00; 22.80--22.90; and 23.18; also a few images near days 25.0 and 27.0. Continuous movies at 1.7 or 2.3 microns during the B and F impacts showed no detectable effects due to these events, though clouds caused brief interruptions, and all other impact events were clouded out. 2.05 - 2.30 micron spectra of the impact site clouds show CH4 absorption, presumably due to CH4 above the impact clouds: simple reflecting-layer models assuming normal atmospheric CH4 abundances above the impact sites give cloud altitudes in the 1 mbar range, though there is considerable variation in the strength of the CH4 bands between impact sites of the same age: the D site shows much stronger overlying CH4 absorption than the E site when both are 0.48 days old, for instance. There is very little CH4 absorption above the A site at age 0.17 days. Spectra of the E site appear to show that the ``halo'' around the site was at a higher altitude than the central ``core''. In contrast to visible continuum wavelengths where the impact sites appeared dark, the sites were invisible at the near-infrared continuum wavelength of 1.58 microns. Follow-up imaging of the impact sites from the IRTF in September 1994, February 1995, and March 1995 showed that considerable structure persisted in the impact-generated clouds even eight months after the impacts. \np \bc {\bf Measurements of Water in the `Re-entry phase' Following Fragments R and W of Comet Shoemaker Levy 9}\\[6pt] \bi A.L. Sprague$^1$, G.L. Bjoraker$^2$, D.M. Hunten$^1$, F.C. Witteborn$^3$, R.W.H. Kozlowski$^3$, and D.H. Wooden$^3$\\[6pt] \ei \ec \bi $^1$ LPL, The University of Arizona\\ $^2$ NASA GSFC \ $^3$ NASA ARC\\[6pt] \ei We have measured the abundance of water seen in spectra following the R and W impacts of Comet Shoemaker Levy~9 into Jupiter's upper Atmosphere. Measurements were made with HIFOGS on board the Kuiper Airborne Observatory that flew out of Melbourne, Australia on July 21 and 22, 1994. The 6.6 $\mu$m \ band of high quantum number rotational states was seen for approximately 5 minutes following both impacts. Abundances are: $\sim$ 5.7 $\times$ 10$^{10}$ \ g for R+12 minutes and $\sim$ 2.2 $\times$ 10$^{10}$ \ g\ for W+10 minutes. These masses are equivalent to ice balls of diameter 50 and 35 m respectively. If we accept the Galileo NIMS conclusion that the explosion of R occurred near the 0.2 bar level then the water is from the bolide rather than the Jovian atmosphere. \np \bc {\bf Polarimetric Imaging Observations of Impact Dark Spots}\\[6pt] \bi B. Suzuki, J. Watanabe, T. Sasaki and H. Kurihara\\[6pt] \ei \ec We carried out a polarimetric observation of traces of the comet impacts on 20th July 1994 with OOPS(Okayama Optical Polarimetry System) attached to the 91cm reflector at Okayama Astrophysical Observatory. The measurements of the degree of linear polarization fragments K and L sites were obtained with four wavelength range(514, 644, 659 and 820nm). The trend of maximum polarization degree of impact dark spot appears about 4 percent which is higher than the Jovian atmosphere situated equal latitude. Wavelength dependence of polarization is not known well from our preliminary results. \np \bc {\bf NUMERICAL SIMULATIONS OF IMPACT OF COMET SHOEMAKER-LEVY 9: COMPARISON WITH OBSERVATIONAL RESULTS}\\[6pt] \bi T. Takata\\ Univ. of Tokyo\\ JAPAN\\[6pt] T.J. Ahrens \& J.D. O'Keefe\\ Caltech\\ Pasadena CA 91125\\[6pt] G. S. Orton\\ JPL\\ Pasadena CA 9110\\[6pt] \ei \ec Numerical simulations of impact of fragments of SL9 were conducted to predict the impact phenomena and the observational possibilities [Takata et al., 1994, Ahrens et al., 1994(1)(2)]. These results are compared with observational results, such as chemical abundance and plume heights (Hammel et al., 1995, Carlson et al., 1995) to investigate the nature of SL9 fragments such as the progenitor size and the origin of the parent body. The comparison suggests that the material of SL9 is primitive, and that sizes of a large fragment and the parent body are $\sim$2 and $\sim 4-5$ km in diameter, respectively. \np \bc {\bf The OAO near-infrared observations of the SL-9 impact to Jupiter}\\[6pt] \bi Satoru Takeuchi\\ Department of Physics\\ Kyushu University\\[6pt] Hitoshi Hasegawa\\ Astec, Inc.\\[6pt] Jun-ichi Watanabe and Takuya Yamashita\\ National Astronomical Observatory of Japan\\[6pt] \ei \ec We observed the impact of comet Shoemaker-Levy 9 into Jupiter by 188cm telescope of Okayama Astrophysical Observatory with a near-infrared camera, OASIS. Flashes originated to the impacts of fragments C,D and K were detected at wavelength of 2.35 micron. We report the detail of these observations and discuss some impact phenomena. \np \bc {\bf Was SL-9 a Jupiter Family Comet or an Escaped Asteroid?\\ (Dynamical Considerations)}\\[6pt] \bi Gonzalo Tancredi and Andrea Sosa\\ Depto Atronomia, Fac. Ciencias\\ Montevideo, Uruguay\\[6pt] \ei \ec SL-9 was an unusual object in many senses. Despite the fragmentation and collision with Jupiter, the dynamics of SL-9 were remarkable. SL-9 experienced a long-lasting temporary satellite capture by Jupiter. The duration of the encounter can not be unequivocally determined due to the chaotic character of the motion, but the evolution can reliably tracked for more than 20 years. There are only two other objects which had suffered comparative but much shorter satellite capture: P/Helin-Roman-Crockett and P/Gehrels 3. Long-lasting satellite captures are a rare phenomena among the observed Jupiter family comets, because there is a very narrow window in the orbital elements phase-space for which it can occur. A useful parameter to classify the candidate orbits is the Tisserand parameter (T), an integral of motion in the Restricted Three Body Problem. Values of T $\sim$ 3 are needed for long-lasting captures. In fact, SL-9 and the two objects mentioned before have T $\geq$ 3. There are also two large populations of objects with T $\sim$ 3, i.e. the Trojan and the Hilda asteroids; but the mean motion resonances with Jupiter (the 1:1 and 3:2 respectively) act as a protection mechanism that prevents the close encounter. Nevertheless, due to mutual perturbations or collisions, an asteroid can escape from the resonance and become a Jupiter approacher. We compare the probability for objects in the three groups to experience a longlasting satellite capture and estimate the frequency of collision with Jupiter. \np \bc {\bf THE REFLECTIVITY OF THE AEROSOL MATERIAL IN THE G, L AND E IMPACT-REGIONS}\\[6pt] \bi Tejfel V.G., Kharitonova G.A., Sinyaeva N.V.,\\ Gajsina V.N., Aksenov A.N., Kirienko G.A.\\ Fessenkov Astrophysical Institute, Kazakhstan National\\ Academy of Sciences, Alma-Ata, 480068 , Kazakhstan\\[6pt] \ei \ec The consequences of the Comet Shoemaker-Levy and Jupiter collisions (CJC) were observed photographically during 16 nights between 17 July and 15 August 1994 with the 1-meter telescope in the high mountain Assy observatory (80 km eastern Alma-Ata, altitude 2750 m). 150 photographic images obtained with the scale 1.8 arcsec/mm were measured on automatized microdensitometer. Computerized images were analyzed to find the planetographic coordinates of the dark impact-regions, their sizes and relative intensities in the blue and red light. The best images (24 and 25 July) in blue and red light with the impact-regions G, L and E placed near the central meridian were studied especially to estimate the minimum relative intensities at the centers of these regions. These intensities are not less 0.62, 0.64 and 0.72 for G,L and E regions respectively on the original images and cannot be less than O.2-0.5 if the smoothing will be considered. The modeling calculations for the most probable characteristics of the cometary solid material that has low albedo have given the estimates of the optical depth for the stratospheric layer formed by dark cometary material. For assumed law of the radial distribution of the dark material amount within observed area of the inpact-regions the sizes of the cometary fragments are derived. They cannot exceed 0.2-0.3 km and this estimate don't contradict to the values derived from other considerations. \np \bc {\bf High temporal resolution near-IR observations of impacts H and Q from Calar Alto and interpretation}\\[6pt] \bi G.P. Tozzi, A. Richichi, \& A. Ferrara\\ Osservatorio Astrofisico di Arcetri\\[6pt] \ei \ec Observations with a fast IR photometer at the 2.2m telescope on Calar Alto have yielded high temporal resolution (sampling typically 100~Hz) lightcurves for some of the impacts, including A, H, Q1/Q2, T (Richichi et al. 1995). In this contribution, we analyze in some detail the data for the main impacts in this set, namely H and Q1. By comparing our H data with those available at other wavelengths, we present estimates of the temperature of the phenomenon and its evolution. In the case of Q1, it is particularly interesting to examine the fine structure of the lightcurve, which is generally lost in other observations available at lower temporal resolution. \newpage \bc {\bf FUV Spectra of SL9 Impact Site G with HST/GHRS}\\[6pt] \bi L. M. Trafton, S. K. Atreya, M. A. McGrath, G. R. Gladstone,\\ J. J. Caldwell, K. S. Noll, H. A. Weaver, R. V. Yelle,\\ C. Barnet, and S. Edgington\\[6pt] \ei \ec Spectra using grating G140L obtained within hours of the impact of fragment G of comet SL9 with Jupiter are presented at effective resolution $4.4$ \AA . Below 1610 \AA\ the spectrum is dominated by emission, with Io's torus being tilted largely out of the field of view. The H$_{\rm 2}$ dayglow spectrum is analyzed and subtracted from Jupiter's spectrum to search for non-hydrogenic emissions such as CO and S. Upper limits are placed on several species of interest and the results are used to interpret impact phenomena. \np \bc {\bf Multiwavelength Observations of S--L 9 Impact Spots on Jupiter}\\[6pt] \bi R. Vasundhara$^1$ \& Pavan Chakraborty$^2$\\ Indian Institute of Astrophysics\\ Bangalore 560034\\[6pt] \ei \ec $^1$e--mail: rvas@iiap.ernet.in\\ $^2$e--mail: pavan@iiap.ernet.in\\[6pt] Observations of Jupiter made at the cassegrain (f/13) focus of the 102 cm telescope at the Vainu Bappu Observatory during 18 -- 22 July 1994 and 13 -- 14 Aug. 1994 are reported. The images taken in July, were recorded through six narrow band filters centered at 4862$\AA$, 4935$\AA$, 5083$\AA$, 6581$\AA$, 8900$\AA$ and 8930$\AA$ with FWHM ranging between 50 to 300 $\AA$. The differential wave length dependence of the scattered light from the impact regions compared to nearby satellites and the surrounding regions on Jupiter are presented. Subsequent, images obtained during 13 --14 Aug, 1994 at 4862$\AA$ and 8930$\AA$ are compared with the July images to look for changes in the wavelength dependence and size of the spots. \np \bc {\bf Comet Shoemaker-Levy 9: A New Class of Object}\\[6pt] \bi Siacho Wang (PMO)\\[6pt] \ei \ec The Comet SL9 has high abundance of sulfur and low abundance of H2O, CO and nitrogen, but most of the fragments were embedded in circularly summetric inner comae from July 1993 until late June 1994, implying that there was continuous and weak outgassing activity. This indicates that comet SL9 is a new class of object which is different from known comets and asteroids. The main features of SL9 are 1) low abundance of H2O, CO and nitrogen; 2) high abundance of sulfur; 3) existence of central coherent body, not swarm of debris; 4) fragile nature; 5( low albedo; 6) containing carbonaceous and silicate material; 7) low volatile object. The existence of this new class object of SL9 indicated the variety of the objects in the solar system. This work was mainly supported by Chinese Academy of Sciences, Chinese National Science Foundation and Chinese Pacific Insurance Co. Ltd. \newpage \bc {\bf Observations and Studies of Chinese Jupiter Watch}\\[6pt] \bi Sichao Wang (PMO), Bochen Qian (BAO) and Keliang Huang (NUU)\\ China\\[6pt] \ei \ec Optical observations: 14 telescopes at 8 observatories or stations joined the CJW. Using the CCD camera and CCD video camera, observations of dark spots have been made at SAO, YAO, PMO, BAO and some stations during the period between June 15 and Sept. 15, 1994. 6 Satellite flash observations have been succeeded at SAO (China) and 9 light curves of Galilean satellites have been obtained. Radio observations: 5 radio telescopes at 5 observatory or stations joined the CJW. During the impact periods, a steady flux density increase of Jupiter was seen at 12cm and 13cm wavelength at BAS and UAS respectively. Possible decametric radio bursts have been detected by BAS. Impact predictions: J. X. Zhang and his colleagues provided the July 7 edition of their heliocentric orbital elements and their impact prediction of SL9. This work was mainly supported by Chinese Academy of Sciences and Chinese National Science Foundation. \np \bc {\bf THERMAL EFFECTS FROM MINOR CONSTITUENTS\\ IN JUPITER'S UPPER ATMOSPHERE AFTER SL9}\\[6pt] \bi Y.~Wang \& K. S. Noll\\ Space Telescope Science Institute\\ 3700 San Martin Dr.\\ Baltimore, MD 21218\\[6pt] R. V. Yelle\\ NASA/Ames Research Center\\ MS245-3\\ Moffett Field, CA 94035-1000\\[6pt] \ei \ec The thermal structure of Jupiter's atmosphere at pressures between 10$^{-6}$ mbar and 100 mbar is calculated for both pre-impact and post-impact conditions, using a radiative-conductive model. For the pre-impact model, we include solar UV and EUV heating, non-LTE cooling by hydrocarbon fundamental bands, cooling by \htwo\ collision-induced opacities, and heating by \chfour\ near-IR and visible bands. The calculated temperature profile indicates that extended heat sources other than known gas opacities have to be present in order to explain the observed temperatures in both the stratosphere and the mesosphere of Jupiter. We added a total heat flux of 175 ergs/\cmt /sec in the stratosphere, 15 ergs/\cmt /sec in the mesosphere, assuming a Chapman profile for each source. This heating is presumably related to the absorption of solar energy by suspended aerosals. Some reports find post-impact temperatures in the stratosphere decreased by as much as several tens of degrees. To study the effects of impact-generated gas on Jupiter's thermal profile we consider a range of models with stratosphere abundances of HCN, NH$_{3}$, and CO taken from published reports. Our studies show that the cooling effects from the minor constituents including HCN, CO, and NH$_{3}$, produced by the impact, are insignificant. The existing thermal balance is dominanted by the main hydrocarbon fundamental bands and \htwo\ collision-induced opacity, and can not be perturbed significantly by the observed quantities of impact-generated gases. \np \bc {\bf Geometrical Model for the Plume Evolution}\\[6pt] \bi J. Watanabe, S. Takeuchi, H. Hasegawa, B. Suzuki and K. Sekiguchi\\[6pt] \ei \ec A geometrical model of the evolution of the impact plume is described. Although impact plumes were basically observed with the HST, three-dimensional structure of the plumes is not clear. Considering the geometrical distribution of the dust grains on the stratosphere at the impact sites, we constract the three-dimensional model of the plumes. By using this model, we discuss the nature of the light curve of the impacts recorded by many grand-based observations with Near-IR wavelength. \np \begin{center} {\bf Temporal and Spatial Variations Among the Fragments of\\ Comet D/Shoemaker-Levy 9}\\[6pt] \begin{it} H. A. Weaver (STScI), M. F. A'Hearn (UMD), C. Arpigny (Li\`ege),\\ P. D. Feldman (JHU), Ph. Lamy (LAS), K. J. Meech (Hawaii),\\ K. S. Noll (STScI), \& T. E. Smith (STScI)\\[6pt] \end{it} \end{center} Observations of comet \mbox{D/Shoemaker-Levy 9} (SL9) with the Hubble Space Telescope began in July 1993 and continued systematically throughout 1994. While a typical spatial brightness profile can be defined for the SL9 fragments, there were also significant deviations from the average behavior. For at least some cases, the deviations are likely due to fragmentation events subsequent to the breakup of the SL9 parent body. There are apparently secular trends in the core brightnesses of some fragments, but generally the variation is less than 50\%. All of the observed fragments showed a strong stretching of the coma near the time of impact as the differential acceleration across the coma due to Jupiter became significant. \newpage \bc {\bf Comet Shoemaker-Levy 9: Support for the Rubble Pile Model}\\[6pt] \bi Paul R. Weissman\\ Jet Propulsion Laboratory\\ Pasadena, CA 91109\\[6pt] \ei \ec The observed behavior of comet Shoemaker-Levy~9 as it orbited and impacted Jupiter was consistent with predictions of the primordial rubble pile (Weissman, 1986) and fractal (Donn et al., 1985) models for cometary nuclei. The comet displayed repeated disruption events along its orbit as sub-nuclei continued to separate from the individual fragments, and complete fading and dispersal of some smaller fragments. Using the rubble pile model, Asphaug and Benz (1994) demonstrated the reassembly of the disrupted comet into $\sim$15-20 fragments, with physically reasonable densities of 0.5 to 1.3 g cm$^{-3}$. Impacting fragments deposited a substantial fraction of their energy in Jupiter's upper atmosphere, consistent with a partially dispersed rubble pile. \np \begin{center} {\bf Narrow-Band Imaging of the Impact Sites on Jupiter}\\[6pt] \begin{it} Dennis D. Wellnitz and Michael F. A'Hearn\\ University of Maryland\\ College Park, Maryland\\[6pt] Ralph Martin and Arie Verveer\\ Perth Observatory\\ Western Australia\\[6pt] \end{it} \end{center} During the month of July 1994, the University of Maryland/Perth Observatory team recorded about 6000 images and spectra of Jupiter, observing from the Perth Observatory in Western Australia. Jupiter was observable from about 1030 through 1630 UT each evening, and we enjoyed an unusually good run of clear weather and near-arc-second seeing during much of impact week. Some of the images were taken through narrow-band filters in methane absorption bands, while others were taken in continuum or wide red filters; the total wavelength range sampled was from about 500 to 900 nm. This data set permits us to look at the reflectivity and absorptivity of the impact spots as a function of height in the atmosphere of Jupiter, and to follow the evolution of individual spots during July 1994. We may also integrate the absorption of a spot over its extent and thereby obtain an estimate of the total mass of the particles comprising the spot. The current status and results of this analysis effort will be presented at the meeting as a poster paper. \newpage \begin{center} {\bf Scattering Properties of Dust Associated with SL9-Jupiter Impact}\\[6pt] \begin{it} N.C.Wickramasinghe\\ University of Wales, Cardiff, U.K.\\[6pt] K.S.Krishna Swamy\\ Tata Institute of Fundamental Research\\ Bombay, India\\[6pt] \end{it} \end{center} The collision of SL9 with Jupiter injected substantial quantities of cometary dust into the Jovian atmosphere at several impact sites, inparticular at the G-site. Therefore the observation of radiation fluxes from the impact site as a function of the time could yield important information on the nature of the dust. In our preliminary investigation, we have calculated the changes in planetary albedos based on optically thin radiation transfer model of an atmospheric haze with optical depth at 5500A and with the size distribution function n(a)=const. a(-3.6). The laboratory measured n and k values for the organic material has been used. The results indicate significant drop in albedo in the UV, but the situation is dependent on the dust loading, the grain parameters and on the composition. We hope to explore wide range of models including multiple scattering. \np \bc {\bf Chemistry of the Shoemaker-Levy 9 Jovian Impact Blemishes:\\ Indigenous Cometary vs. Shock-Synthesized Organic Matter}\\[6pt] \bi Peter D. Wilson and Carl Sagan\\ Laboratory for Planetary Studies\\ Cornell University\\ Ithaca, NY 14853\\[6pt] \ei \ec We find that the optical constants of the aerosols in the dark impact blemishes, as measured by West et al. (1995), are a near-identical match to Murchison organic residue. This organic matter could be either (1) indigenous to the impacting comet, or (2) shock-synthesized from the Jovian atmosphere. A 1-km comet will produce an earth-sized blemish with $\tau=1$ if 5-15\% of its volume is deposited into the atmosphere as particles with radii r=0.1-1.0 microns. Based on our most analogous charged-particle irradiation experiments, the energy deposited into the Jovian atmosphere by the same-sized impact is able to produce only enough organic matter to reach $\tau=0.25$. This estimate, however, could easily be in error by an order of magnitude, so we cannot conclusively exclude the shock-synthesis mechanism. Given the high degree of similarity between the aerosols and the organic residue extracted from the Murchison meteorite, though, we conclude that the organic matter in the blemishes is most likely debris from the impactors. \np \vspace*{-1cm} \centerline{\bf Observations of the Jovian Satellites During Comet P/Shoemaker-Levy 9's} \centerline{\bf Impact with Jupiter } \vskip .1in \centerline{L. M. Woodney, R. Meier, M.F. A'Hearn, and D. Wellnitz} \centerline{University of Maryland} %\centerline{and} \medskip \centerline{T. Smith, A. Verveer, and R. Martin} \centerline{Perth Observatory} \vskip .1in Once it was known that the impacts of the fragments of comet P/Shoemaker-Levy 9 would occur behind the limb of Jupiter it was expected that reflections off of satellites would be one of the best ways to view the entry flashes from Earth. However, the results of the attempts to observe this effect were disappointing. To date, no one has reported a significant detection of a flash, but there are several reports of possible flashes. Each of these detections require confirmation from other observers to establish whether or not they are noise. Our own data contain two of these possible flashes. We observed Io, Europa and/or the limb of Jupiter during the expected impact times of fragments D, E, and K from two sites in Western Australia. At the Perth Observatory 61 cm telescope we used a CCD camera and broad band filters, while at Mt. Singleton we used an unfiltered, high-speed, blue sensitive photometer and a 14 inch Celestron. Our best photometer observations are from the time of the D impact. These data also include our best possibility for an observed flash. There is a 7\% increase in the brightness of Io which lasts several seconds. There is a second possible flash at the time of impact of E, which is seen in both the photometer data and a CCD image, but both detections could easily be explained by noise. To establish whether or not these events are real, high signal to noise data from other observers is needed. The luminosities that we derive from both possible flashes are two orders of magnitude greater than seen by Galileo for other events. This implies that the spectra of these flashes were either very different from those of black-bodies, or possibly that they were like those of very hot black-bodies. Our upper limit for the luminosity of impact K of \mbox{6 $\times 10^{23}$ erg sec$^{-1} \mu m^{-1}$} at 945 nm is only a few times brighter than the peak observed by Galileo. Perhaps better data reduction will reveal a flash. \np \begin{center} {\bf Physical Properties of Swarmed SL9 Fragments at Impact}\\ \vspace{0.3in} Xingfa Xie and Michael J. Mumma\\ NASA/GSFC \vspace{0.1in} Kevin M. Olson\\ George Mason University\\ \end{center} We present results from an N-body simulation of the swarms made of tens-meter-sized objects, beginning at apojove and ending seconds before impact. Our simulation shows the swarm to be stretched into a long train along the direction of orbital motion, with a high mass concentration at the center. The initial sizes of the swarms at apojove are estimated to be in the range of 20-50 km for swarm masses of $10^{13}-10^{15}$ g, based on the light curves obtained by Galileo. Incorporation of particle collisions into our model is currently in progress. \np \bc {\bf Explanation of Flashes and Bright Flare in IR-Lightcurves of Shoemaker-Levy 9 Impacts: Comparison between Numerical Simulations and Observations}\\[6pt] \bi Takashi Yabe, Masakazu Tajima, Sho Sasaki, Yutaka Abe, Feng Xiao,\\ Takayuki Aoki, and Jun-ichi Watanabe\\[6pt] \ei \ec The strong IR emission and the preceding flashes at Comet Shoemaker-Levy~9 impacts into Jupiter are studied based on the numerical simulation of the explosion process. 2-D and 3-D simulations of impact and explosion processes are performed using highly accurate hydrocode ExCIPHER. Energy deposition at the shallower depth along an elongated trajectory of cometary entry can generate the first rapid rising fireball as well as a subsequent broad plume. Calculated time intervals are compatible with the secondary flash and the strong bright flare in IR-lightcurves. Obtained temperature evolution can explain the observed rapid decay of the strong flare. \np \bc {\bf CCD Methane Band Modelling of A, H, L and R Impacts}\\[6pt] \bi Padma A. Yanamandra-Fisher, Jose Luis Ortiz and Glenn S. Orton\\ Jet Propulsion Laboratory, Pasadena, CA 91109\\[6pt] \ei \ec Time series of impacts (H, L, R) at 0.89 $\mu$m and (A, H, L) \mbox{0.945 $\mu$m} indicate that the main event or the major brightening of the plume occurred and is in phase with the peak of the event as observed at 2.3 $\mu$m. However, the first and second pre-cursors are not always evident in the CCD methane band data. We are presently working on modelling these events to establish the spectral energy distribution of the fragments. Our data set comprises of data from Calar Alto, La Palma and Table Mountain observatories. \np \bc {\bf Three strong Jovian decametric radio bursts from impacts}\\[6pt] \bi Xi-Zhen Zhang$^{1}$, Jin-Lin Han, \& Qi-Bin Li\\ Beijing Astronomical Observatory\\ Chinese Academy of Sciences\\ Beijing 100080, P.R. China\\[6pt] \ei \ec \bi $^{1}$email: zxz@bao01.bao.ac.cn\\[6pt] \ei Three strong decametric radio bursts ($>$20db), undoubtedly related to the impacts of fragments G, K, and W of Comet Shoemaker-Levy 1993e (SL-9) on Jupiter, have been detected during the impact week at Xin-Xiang temporary Jovian Decametric Watch Station of Beijing Astronomical Observatory. All of them are narrow band events occurred at about 26.0 and 28.5MHz, and have a long duration of at least several minutes. Their completely different characteristics, (ie. strongest one before G impact, immediate response to K impact, and switching bursts after W impact), are shown in this report. The project is supported by the National Natural Science Foundation of China. \np \bc {\bf On Jovian Decametric Radio Bursts of the Great Comet Crash}\\[6pt] \bi Xi-Zhen Zhang , Lin-Lin Han, Qi-Bin Li , Pei-Nan Jiao, Jun-Hu Du\\[6pt] \ei \ec Strong decametric narrow-band radio bursts (N events) and broad-band storms, produced by impacts of fragments of Comet Shoemaker-Levy 1993e (SL-9) on the Jupiter, have been detected during our observations from July 17 to 22, 1994 at the Xin-Xiang temporary Jovian Decametric Station (longitude = -113.8 degrees, latitude = 35.3 degrees) of the Beijing Astronomical Observatory. Observations were carried out in the scanning mode in the frequency range from 24.0 OMHz to 28.5 MHz. Signals were detected from 10 narrow bands in a step of 0.5 MHz, and each band has a bandwidth of 0.1MHz and a sampling time of 0.1 second. Plots of relative signal intensity of these bursts at 10 frequencies between 24.0 and 28.5 MHz has been published (Zhang et al., 1994 and Han et al., 1994). In this paper we report some preliminary analysis results on three strong radio bursts, which were apparently produced by G, K and W fragment impacts on July 18, 19 and 22, respectively. Also some spectrum analysis are presented on decameter storms which appears to be related to the impact of fragment S$=$5 on July 21. \np \bc {\bf THE PREDICTION OF THE IMPACT OF COMET SHOEMAKER-LEVY 9 ON JUPITER}\\[6pt] \bi J.-X. Zhang, Q. Wang, J.X. Yang, S.C. Wang, X.Z. Chen\\ Purple Mountain Observatory, Nanjing, China\\[6pt] \ei \ec Using numerically self-established dynamical model for solar system objects, exploring method and making software, we successfully sent out several times of prediction from April to July 1994, and the predictions mainly coincided with actuality. The method and theory of the predictions are expounded briefly in this paper, and the precicted impact items are compared and analyzed with actual accented impact times newly confirmed. The nuclei's movement when they were in the vicinity of Jupiter and the impact positions are also discussed. \np \bc {\bf THE LIGHT CURVES OF GALILEAN SATTELITES DURING THE COLLISIONS OF COMET SHOEMAKER-LEVY 9 AND JUPITER}\\[6pt] \bi Hongnan Zhou\\ Dept. of Astronomy\\ Nanjing University\\ Nanjing 210093\\ P. R. China\\[6pt] \ei \ec In this paper, we present the light curves of Galilean Sattelites during the fragments D=19, E=18, K=12, N=9, P2=8b and S=5 impact with Jupiter. \np \bc {\bf THE IMPACT TIME OF FRAGMENT P2=8b}\\[6pt] \bi Hongnan Zhou\\ Dept. of Astronomy\\ Nanjing University\\ Nanjing 210093\\ P. R. China\\[6pt] \ei \ec According to the light curve of Io during the fragment p2=8b impacts with Jupiter, we obtained the precise impact time of fragment p2=8b. \end{document}