SESSION 01 ....... Comet Shoemaker-Levy 9 I Monday, 8:30 - 10:00 Crystal Ballroom M. Festou and H.A. Weaver, Moderators 01.01 Weaver H. A.* Noll K. S. Storrs A. D. Smith T. E. A'Hearn M. F. Arpigny C. Feldman P. D. Boice D. C. Stern S. A. Lamy P. L. Larson S. M. Levy D. H. Scotti J. V. Marsden B. G. Meech K. J. Shoemaker C. S. Shoemaker E. M. Sekanina Z. HST Monitoring of Comet P/Shoemaker-Levy 9 The Hubble Space Telescope (HST) first observed comet P/Shoemaker-Levy 9 (SL9) on 1 July 1993, and then began a systematic monitoring campaign in late January 1994 that continued through the impact week in mid-July 1994. During the campaign a total of 39 HST orbits were devoted to imaging of the comet, and 6 orbits were devoted to UV spectroscopy with the Faint Object Spectrograph (FOS) in the wavelength range from 2223 - 3278 nagstrom. The images were used to estimate the sizes of the nuclei, examine carefully the near-nucleus morphology to search for further fragmentation events and outgassing activity, monitor the temporal variability, and measure the V-R colors in the inner comae of several nuclei. Results from several different image deconvolution analyses indicate that the diameters of the larger nuclei were in the range of about 2 - 4 km (assuming a geometric albedo of 4%), but all of these techniques impose constraints on the core behavior of the coma brightness profile that are not necessarily valid. Most of the nuclei displayed spherically symmetric comae of approximately 0."6 in radius from July 1993 until mid-July 1994, at which time the comae became highly elongated along the direction of the train. There is clear evidence for continuing fragmentation of the nuclei subsequent to the July 1992 breakup of the original body, which seems to argue against the "swarm" model for most of the fragments. The spectroscopic observations of SL9 have not shown any evidence for OH emission, which might be expected if SL9 is a water-laden object. Spectra taken on 14 July 1994 show strong Mg II emission in one two-minute segment followed by a three-fold increase in the continuum about 18 min after the appearance (and disappearance) of Mg II. The continuum enhancement lasted for less than 20 min. These latter spectral observations were made when SL9 was about 50 R(sub)J from Jupiter and may correspond to the time when the comet crossed the Jovian magnetopause. 01.02 Benner L. A. M.* McKinnon W. B. Dynamical Evolution of P/Shoemaker-Levy 9 We have investigated the orbital evolution of P/Shoemaker-Levy 9 by integrating its motion in the general four-body Sun-Jupiter-Saturn-comet problem, using the orbital elements determined by D.K. Yoemans and P.W. Chodas (posted on the P/Shoemaker-Levy 9 public account). We have now simultaneously integrated nineteen fragments (posted February, 1994) back to the 1992 perijove to test the effects of self-gravity (suggested by Benz and Asphaug) and possibly constrain the masses of the fragments. A general convergence within approximately 0.2 R(sub)J of the train center shortly after perijove is observed, but in general, improved orbital elements are necessary to achieve a more compact convergence, so no constraint on the fragment masses can be inferred yet. Prior to perijove, Shoemaker-Levy passed through the inner halo of Jupiter's ring at approximately 1.6 R(sub)J. Collisions with ring particles may have weakened the nucleus and assisted tidal disruption, or caused the disruption as the comet is apparently not strength dominated. The motion of each fragment was treated as a test case of the pre-disruption parent body's evolution and was integrated backward. Capture durations vary between approximately 6 and approximately 40 P(sub)J (P(sub)J = 1 jovian year), with a median near approximately 9 P(sub)J. The motion of the comet is chaotic, with a Lyapunov time of approximately 30 yr, so no definitive capture date can be inferred. The only robust inference for its pre-encounter heliocentric origin is that the orbit was not one of either high inclination or high (>0.5) eccentricity. Secular solar perturbations cause Shoemaker-Levy's jovicentric orbit to alternate between intervals of low eccentricity (e similar to 0.1 - 0.3) and high inclination (i similar to 90 degrees), and near-parabolic eccentricity and lower (either prograde or retrograde) inclinations (while its jovicentric semimajor axis and angular momentum perpendicular to Jupiter's orbital plane are approximately constant). Consequently, prior to disruption Shoemaker-Levy's perijove oscillated from a maximum of approximately 0.15 AU to a minimum well within the orbit of Callisto, indicating multiple earlier close flybys may have occurred. Ultimately solar perturbations increased Shoemaker-Levy's eccentricity and decreased its perijove sufficiently for disruption in 1992 and collision in 1994. This work supported by NASA grant NAGW-432 and NGT-50629. 01.03 Lisse C. M.* A'Hearn M. F. Esterle P. A. McFadden L. A. Weaver H. A. Woodney L. M. Modeling of UBVRIJK' Observations of P/Shoemaker-Levy 9: Implications for the Dust Size Distribution, Emission History, and Icy Composition 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), Cerro Tololo Interamerican Observatory (CTIO), and the NASA/Infared Telescope Facility (IRTF). Extended comae and dust tails many arc-seconds in extent were detected for 10 of the cometary nuclei. Observations to date have yielded only non-detection upper limits for gas production from the comet. But the observed pre- impact dust in the tails, trails, and debris fan associated with 1993e had to originate at some point in time and space, presumably at/near the July 1992 perijove that first captured the comet into a Jupiter-centered orbit and fractured the parent body. The lack of activity due to low local equilibrium temperatures suggests that any observed dust has a substantial icy component to its composition. The behavior of the dust during the July 1994 impact will place strong constraints on its properties, and demonstrate its behavior in a strong magnetic field environment. We have fit the UBVRIJK images to 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 (Beta), and the particle size (Beta) distribution. The models are poorly constrained unless observations over a large angular scale and a large time range (>1 month) are made. We present preliminary conclusions concerning the emission history and dust particle size distribution of P/Shoemaker-Levy 9 from the dynamical models. We have also combined the images into spectra. We 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 are made. We present preliminary conclusions concerning the silicate:carbon:ice composition of the grains. 01.04 Ahrens T. J.* Takata T. Friedson A. J. Orton G. S. Radiative Signatures and Plumes from Impact of Comet Shoemaker-Levy 9 on Jupiter Pre-impact diameters of Comet Shoemaker-Levy 9 fragments (SL9) are computed by comparing observed maximum height of plumes and their radiance with detailed Smoothed Particle Hydrodynamic (SPH) modeling of impact in three dimensions [Takata et al., Icarus, 109, 3-19, 1994; Ahrens et al., GRL 21, 1087-1090 and 1551-1553, 1994a,b]. Comparison between preliminary absolute peak radiances of the plume from impact of fragment R observed by the NASA/Infrared Telescope Facility SL9 Team with the MIRAC2 camera (Hoffmann et al., Infr. Phys. Tech. 35, 175, 1993) at 7.85, 10.3 and 12.2 microns with SPH power versus wavelength yields (using logarithmic interpolation at 10 microns) a diameter of approximately 1.3 km. In contrast, maximum plume height after impact is directly proportional to fragment energy, for example, inferred from images of the G impact recorded by the Hubble Space Telescope (Hammel et al. 1994, Science, in prep.) yields a height above the ammonia cloud deck of approximately 3300 km. Interpolating previously maximum plume height calculated for 0.4 and 2 km diameter fragments yields a fragment diameter of 1.7 km (assuming a density of 1 g/cm^3). Using these values to calibrate the relative sizes of fragments [Weaver et al., Science, 263, 787, 1994] yields an estimate of the progenitor SL9 diameter of 3 to 3.4 km and a total impact energy of 2.5 to 3.6 x 10^30 ergs or 6 to 9 x 10^7 Mton of TNT equivalent impact energy for the entire SL9 fragment chain. The SL9 progenitor diameter is less than the seven short-period comet nucleii in Luu's [Pub. Astron. Soc. Pac. 106, 425, 1994] catalog. Comparisons between other aspects of the SPH model, such as the penetration depth, will be made as new observational data become available. 01.05 Schenk P.* McKinnon W. B. Characteristics of Split Comets: The Fossil Record from Crater Chains on Callisto and Ganymede Crater chains on the surface of Jupiter's large moons Callisto and Ganymede represent a unique sample of ancient, tidally split comets. These impressively straight chains, or catena, can be up to 700 km long and consist of between 6 and 30 impact craters. No other type of crater clustering has been recognized. Characteristics of these chains closely resemble those of P/Shoemaker-Levy 9 at the time of discovery. Positions of craters within chains exhibit no more than one crater diameter deviation from the best-fit line through the chain. The largest craters are located in the center portion of the chain. The chains approximate great circles but can have curves equivalent to 30 degrees colatitude small circles, consistent with nonvertical impact of a linear chain on a rotating sphere. A reexamination of the Voyager images and detailed mapping indicates that there is a total of 8 such chains on Callisto that are clearly unrelated to secondary cratering (3 additional chains are classified as of uncertain origin). Assuming a mean surface age of 4 b.y. for Callisto, we obtain a frequency of 1 splitting event every 150 to 200 years. Three similar chains have also been identified on the younger surface of Ganymede. We have begun a study of the detailed morphology of these craters in order to assess the role of dispersed comet fragments on cratering in the Jovian system, and to characterize the internal properties of comets/asteroids and their fragmentation. Craters within these chains range from 4 to 36 km in diameter. Using appropriate scaling laws, and an impact velocity of approximately 15 km/s at Callisto, we calculate cometary fragment size range of 0.2 to several km, assuming a density of 1 gm/cm^3. Crater morphology may also provide limits on the structure of individual fragments. Central peaks, rimwall slopes and flat floors are recognizable in all the crater chains (within the resolution limits) and have dimensions consistent with those of normal craters. This implies that split comet fragments are not loosely bound disrupted clusters (like many secondary craters), although they may range from solid cohesive fragments to closely bound rubble piles. 01.06 Hammel H. B.* Dowling T. E. Harrington J. Mills J. R. Beebe R. F. Simon A. A. Huber L. F. Ingersoll A. P. Toigo A. Orton G. S. West R. A. De Jong E. Karkoschka E. Kuehn D. M. HST Imaging of Jupiter's Atmosphere in July 1994: Dynamical Effects from the Impact of Comet P/Shoemaker-Levy 9 In mid July 1994, fragments of the comet P/Shoemaker-Levy 9 plunged into Jupiter over a period of several days. We used the Hubble Space Telescope to image Jupiter before, during, and after the impacts to search for atmospheric phenomena created during the collisions. Many effects on Jupiter's atmosphere were detectable. For four separate events (A, E, G, and W), fireball plumes were detected rising above the limb of Jupiter; some of these plumes reached heights of 4000 kilometers. The plumes were visible in Jupiter's shadow, probably in thermal emission; above the shadow, they reflected sunlight. We observed several fresh impact sites, and detected transient expanding rings around several sites, most likely caused by horizontal propagation of an atmospheric wave. Estimates of the propagation speed will be reported. Thin ejecta blankets sometimes extended up to 16,000 km from the impact sites. The distribution of material was asymmetric; the patterns were consistent with ejection back along the sloping path of the incoming projectile. Several features evolved throughout the week of impacts due to the jovian winds. We also imaged impact sites over a period of several weeks to watch the long-term effects of atmospheric circulation on impact-created debris. In this talk, we will present an overview of the dataset and the results from our program. Detailed interpretation of the data will be presented in other talks in the session. These NASA/ESA Hubble Space Telescope observations were supported in part through grant GO-5624.08-93A from the Space Telescope Science Institute (operated by AURA Inc. under NASA contract NAS5-26555). 01.07 de Pater I.* Graham J. R. Jernigan G. Brown M. Liu M. Marcus P. Fomenkova M. Ingersoll A. Orton G. Infrared Observations of the Comet SL9/Jupiter Impacts at Keck We observed the SL9 impact with Jupiter on July 16-21 with the near- infrared camera (NIRC) mounted on the W.M. Keck telescope. We focused on imaging experiments, at wavelengths between 1 and 4 micrometers. Our most significant observation is the continuous monitoring of the fragment R event at 2.3 micrometers. Monitoring began 25 minutes before the impact of R, and continued until 22 minutes after. The resultant movie has approximately 8 frames per minute, and shows two flashes at the approximate time of impact, followed by the plume rotating into view. We will show and discuss the movie and lightcurve of the R event. In addition, we will show images of Jupiter's disk at 7 different infrared wavelengths which show the time evolution and vertical structure in the atmosphere of the various impact sites. We further have images of several cometary fragments (M, K, and W), and of Jupiter's ring (during impacts C and M, and afterwards). 01.08-INV Belton M. J. S. Chapman C. R.* Johnson T. V. Heffernan C. M. Klaasen K. P. Galileo Imaging Team Galileo Imaging of the Shoemaker-Levy 9 Impact Sites The Galileo Solid State Imaging SSI Camera was used to observe directly the impacts of fragments K, N, V, and W. To capture any sufficiently bright bolides, fireballs, or other L luminous phenomena with different sensitivities and time resolutions, two new camera modes were implemented -- an on-chip mosaicking of 2 1/3 sec. time-lapsed images and a diagonal drift-scan mode. Brief samples of data from the K, N, and W impacts have been returned to Earth. A luminous event has been detected for K from approximately 10:24:15 to 10:25 UT, reaching a peak brightness (in the near-IR) about 10% that of E total Jupiter (as seen from the same vantage point, 50 deg. phase, 1.5 AU from Jupiter). An event was observed for W, commencing at 8:06:12 UT, and lasting for at least 2 more images taken at 2 1/3 sec. intervals, which reached a peak brightness about 1% the brightness of Jupiter (green filter). Data return for the N impact is not yet sufficient to determine whether or not there is an indication of an event. We have decided not to return data for V, which were taken in a less favorable observing mode. It is not yet clear which parts of the impact phenomenology have been observed for K and W (e.g. bolide or fireball) but we expect to have much additional data available for at least the K impact by the time of the DPS presentation. We will also describe plans for returning the remaining data during the months extending to the end of January 1995. 01.09 Martin T. Z.* Tamppari L. Orton G. S. Claypool I. Travis L. Galileo PPR Observations of Shoemaker-Levy 9 The Galileo spacecraft Photopolarimeter Radiometer (PPR), a hybrid visual/thermal IR instrument designed primarily to measure properties of the Jovian atmosphere, was employed for SL9 as a staring high-speed photometer at 945 and 678 nm, taking advantage of Galileo's direct view of the impact point. Jupiter subtended 0.6 mrad within the 2.5 mrad circular field of view. The PPR was able to acquire data at times when no other Galileo optical instruments could operate. The impacts of fragments B, H, L, Ql, and S were observed for 41 m each with a sample time of 0.23 sec. The H, L, and Ql events provided good light curve and timing information. Initial flashes occurred at these times (for eardlbased observers): H: 1994/199 19:31:58 UTC L: 1994/200 22:16:48 Ql: 1994/201 20:13:52 These data likely represent thermal emission from the brief initial pass of comet fragments through the atmosphere, followed immediately by an expanding and cooling "fireball." The Ql flash appeared 3x brighter at 678 nm than at 945 nm, with a faster decay at the shorter wavelength. Initial temperatures above 10^4 K are implied. (A graph of these events appears on hard copy.) 01.10-P Yeomans D. K. Chodas P. W. Comet Shoemaker-Levy 9 in Orbit About Jupiter The collision of comet Shoemaker-Levy 9 with Jupiter has focused attention upon the cometary formation process and the history of cometary motions within the solar system. At least some comets appear to be extremely fragile structures. In addition to the Jupiter tidal disruption of comet Shoemaker-Levy 9s on July 7, 1992, comet Brooks 2 was disrupted by Jupiters tidal forces in 1886. Although Brooks 2 was not captured by Jupiter, temporary captures of periodic comets by Jupiter are not particularly unusual. During the 1800-2200 time period, the following periodic comets either have been, or will be, in temporary orbit about Jupiter: Shoemaker-Levy 9, Helin-Roman-Crockett, Oterma, Gehrels 3, Smirnova-Chernykh, Haneda-Campos, Helin (1987w), and Kojima. Apart from the record close Jupiter approach of comet SL-9 on July 7, 1992 (1.3 Rj) and the collision in July 1994, the next closest Jupiter approach was that of Gehrels 3 in August 1970. Although Gehrels 3 did not pass closer than 3 Rj to Jupiter, its osculating perijove distance for an epoch in February 1971 was temporarily well below Jupiters radius. Although only comet Shoemaker-Levy 9 collided with Jupiter, solar perturbations on comets in Jupiter orbit can easily reduce a comets perijove distance to allow a collision. Using the orbital history of Shoemaker-Levy 9 as an example, the Jupiter capture process is discussed. 01.11-P Rettig T. W. Hahn J. Tegler S. C. Mumma M. J. DiSanti M. Hubble Space Telescope Observations of Comet Shoemaker-Levy 9 Subnuclei: Solid Bodies or Swarms? We present a preliminary analysis of comet Shoemaker-Levy 9 images taken with the Hubble Space Telescope Wide Field (WF) and Planetary Cameras (PC) during January, March, May, June and July 1994. The WF and PC images have resolutions of 0.10 and 0.046 arc sec, respectively. The high spatial resolution of the images allows us to probe the dust distribution in the inner coma of each subnucleus through an examination of continuum surface brightness distributions. We are using the observed magnitude variations and surface brightness distributions of the inner comae to determine whether the various impacting subnuclei consisted of kilometer sized central bodies or swarms of meter-sized cometesimals. We suggested (Rettig et al. BAAS 1994) that as the original cometary nucleus approached perijove in 1992, the nucleus fragmented into a cloud of cometesimals that was quickly stretched out in a 'tube' along the tidal direction. After leaving the Roche limit, the decreasing tidal force permitted self-gravity to re-focus material to form (approximately 20) 'swarms'. Depending on swarm mass and particle relative velocities, several types of comet 'fragments' may have developed. The swarms might have gravitationally re-collapsed into central subnuclei or they may have remained as loosely bound swarms of particles that could have been disrupted at large distances from Jupiter, prior to impact. For subnuclei that consisted of loosely formed swarms of particles, the effects of tidal disruption were predicted to be observable prior to Jovian impact as variations in both surface brightness distributions and magnitudes. Even the recondensed subnuclei were expected to disrupt again at the tidal limit and were not expected to penetrate much below the stratospheric levels of the Jovian atmosphere. Evidence of swarm-like structures will provide information on the physical structure of comet nuclei and will provide constraints on comet accretion processes that existed some 4.5 billion years ago. This research is supported by an STScI grant to the University of Notre Dame. 01.12-P Rauer H. Osterloh M. Low Resolution Spectra of Comet Shoemaker-Levy 9 (1993e) The activity of cometary nuclei is found to be restricted to descrete areas on the surface. The difference between active and inactive regions may be caused by the evolution of the comet during its perihelion passages, or may be linked to processes during its formation. Assuming comets are made of several planetesimals, physical and/or chemical differences between the cometesimals may cause the observed differences in activity. Up to now, the question of homogeneity of cometary nuclei could not be addressed in measurements of comets. The break-up of comet Shoemaker-Levy 9 into a chain of individual nuclei offers the unique possibility to study possible differences of parts of a cometary nucleus. Low resolution spectra (16 angstrom/pixel) of comet Shoemaker-Levy 9 have been obtained on April 15 1994 at the 2.2m telescope at ESO, La Silla, using EFOSC 2. The spectral range covers 3600 angstrom - 9200 angstrom. The slit of 5.7 arsec length and 5 arcsec width was placed along the train of nuclei. In this way 11 spectra of the train have been obtained to search for possible differences in the dust colour of the individual nuclei. 01.13-P Chen J. Jewitt D. Luu J. Mauna Kea Observations of Split Comet Shoemaker-Levy 9 Split comet Shoemaker-Levy 9 has been observed from Mauna Kea at regular intervals since its discovery in March 1993. Systematic observations with a charge-coupled device on the University of Hawaii 2.2 meter telescope show the photometric and morphological evolution of the fragments over the 16 month pre-impact period. Apart from the progressive separation of the fragments, the most prominent change observed is the decrease in the amount of dust associated with the comet. Individual dust tails became prominent in early 1994 but subsequently faded. As we reported at last year's DPS meeting, no clear evidence for embedded nuclei can be discerned in the Mauna Kea data. Spectra from the 3.6 meter CFHT and 10 meter Keck telescopes were obtained to search for gas (OH, CN, N(sub)2^+, CO^+) in the 3000 angstrom to 4500 angstrom wavelength region. No evidence for emission was found. We will present an overview of the temporal development of the fragments prior to their plunge into Jupiter. 01.14-P Peterson B. A. Wehinger P. A. Wyckoff S. Spectroscopy of Comet Shoemaker-Levy 9 and Jupiter Spectroscopic observations of Comet Shoemaker-Levy 9 and Jupiter were acquired during the period 1994 July 16-23 using the Mt. Stromlo Obs. 1.9-meter telescope and a long slit CCD spectrograph. We shall compare the spectra of the fragments of comet Shoemaker-Levy 9 with those of P/Halley observed at similar heliocentric distances (4.8 AU). In addition, we report on slit spectra taken at the eastern limb of Jupiter in an attempt to search for evidence of the effects of the collision of selected larger fragments in the outermost layers of the Jovian atmosphere. This research is supported in part by the NASA Solar System Exploration Division and the NSF U.S.-Australian Cooperative Science Program. 01.15-P Chernova G. P. Birkle K. Kiselev N. N. Jockers K. Imaging Photometry, Polarimetry and Color of Comet Shoemaker-Levy 9 Comet Shoemaker-Levy 9 was observed with the ESO 1m-telescope and the focal reducer of the Max-Planck-Institute for Aeronomy from April 27 to May 1. During this interval the phase angle wa.s always less than 0.4 degrees. ,About 60 useful images of 5 minutes duration were obtained in the g, r, and i filters of the Gunn system. The field of view was 14.5 x 9.6 arcmin and the scale 1.6 arcsec pixel^-l. For the night of April 27/28 the following Gunn g magnitudes have been derived (the fluxes are taken in square boxes of 5 x 5 pixels, i.e. 8 x 8 arcsec, corresponding to 21000 x 21000 km at the comet): 20.6 A(21), 20.0 B(20), 20.2 C(l9), 19.3 E(17), 19.6 F(16),18.4 G(15),18.8 H(14),18.5 K(12),18.9 L(ll),l9.1 P2(8b), 19.3 R(6), 18.9 S(5), 19.5 W(1). The Gunn G magnitude of P1, Q1 and Q2 together, measured in a square box of 11 x 11 arcsec is 17.7. The colors of the individual comet fragments are the same within the error limits. This indicates a homogeneous nucleus of the parent comet. In the night from May 12 to May 13 comet Shoemaker-Levy 9 was observed with the prime focus camera of the 3.5m-telescope of the German-Spanish Astronomica1 Center, Calar Alto, Spain, through a rotatable polaroid and a filter similar to the R filter of the Cousins system in order to obtain a polarimetry map of the comet. At that time the phase angle was 2.6 degrees. Four images of 20 minutes duration were secured, with polarization directions 0 degrees, 45 degrees, 90 degrees, and 135 degrees. The field of view was 7 x 7 arcmin and the scale 0.41 arcsec pixel^-l. Since the night was not photometric it will not be possible to extract an accurate polarization map but we might be able to judge about polariza.tion differences between the individual nuclei and their tails and to compare them with the color variations. 01.16-P Yabe T. Xiao F. Zhang D.-L. Sasaki S. Kobayashi N. Abe Y. Terasawa T. Effect of EOS on Break-up of Shoemaker-Levy 9 Entering the Jovian Atmosphere Break-up of Comet Shoemaker-Levy 9 entering Jovian atmosphere was studied with highly accurate hydrocode ExCIPHER[1] by changing the equation of state (EOS) of the comet[2]. The comet of radius 1.5km was completely destroyed around the atmospheric pressure of 10 bar which is shallower than that of the other simulations[3,4]. Furthermore, the behavior of break-up is quite different from them. This behavior depends on the type of EOS . For hard material like water and ice, the impact of Jovian atmosphere caused incompressible surface wave propagating along the comet surface thus enhancing ablation loss even at a low pressure atmosphere. For ideal EOS, however, the surface wave did not appear since the comet was compressed upon impact and hence the ablation loss around 5 bar was quite low. Although the comet was broken into moderate pieces at 10 bar, most of the energy had already been lost well before the break-up. Surprisingly, however, the final disintegration occurred around 10 bar for tested EOS and even for planar geometry. This may be because the disintegration is triggered by a hole created along the central axis and the comet is torn off when the atmospheric gas penetrates through the comet causing turbulent now behind it. A hole of this kind can easily develop because even a small concave structure can grow into a larger one by the focusing of flow through conical geometry. The subsequent explosion process was also simulated by the same code. In the first 100 second, a plume followed by a fireball propagates above 1000 km and then the plume alone is ejected higher in the sky like an umbrella. The rest part expands quite slowly over 10000 km and this structure lasts for more than 1000 second. These two sequences might be related to the two subsequent increases of observed infrared signals. [1] Yabe, T. et al. (1994) Nucl. Des. Engnrg. in press. [2] Yabe, T. et al. (1994) J.Geomag.Geoelec. 46, 657-662. [3] Mac Low, M. and Zahnle, K (1994) Ap. J. Lett. in press. [4] Ahrens, TJ. et al. (1994) Geophys. Res. Lett. 21, 1087-1090. 01.17-P Wyckoff S. Ferro A. Spectroscopic Observations of Comet Shoemaker-Levy 9 and Jupiter Long slit spectra of selected fragments of Comet Shoemaker-Levy 9 and of Jupiter were acquired with the 4.5-meter Multiple-Mirror Telescope using the red channel spectrograph. Observations were obtained during the week of the SL9's collision with Jupiter. The spectra of the fragments will be characterized. We shall compare the SL9 spectra with those of P/Halley observed at similar heliocentric distances (4.8 AU). This research is supported in part by the NASA Solar System Exploration Division. 01.18-P Festou M. C. Lelouch E. On the Detection of Gaseous Species in Comet Shoemaker-Levy 9 Prior to Its Impact with Jupiter Comet P/Shoemaker-Levy 9 was observed on five consecutive nights with the 30m IRAM antenna, from 16 July till 21 July 1994. The instrumental setting allowed to simultaneously monitor the gaseous emissions of CO and HCN in the 2 mm window until the comet disappeared behind the planet disc, then to switch to another observing program. If in July 1994 the comet sub nuclei break as they did in 1992 after entering the Roche limit of the planet, then a large cloud of dust particles will form and slowly expand into space. Large amounts of gas might be released, either at the time of breakup or immediately after, when large areas of fesh comet snow are exposed to sunlight. Such an event could occur anywhere during the last hour prior to the impact. At the time of impact, this cloud might be up to about 1,000 km in diameter, and very bright, especially in CO light. The observing geometry is such that the comet activity at mm wavelengths can be monitored until the last few minutes before the impacts, maximizing thus the chances to detect a gaseous emission from the comet. This paper will be given only if positive results are obtained. 01.19-P McFadden L. A. A'Hearn M. F. Esterle P. A. Lisse C. M. Weaver H. A. Woodney L. M. Multi-Wavelength Imaging of Comet P/Shoemaker-Levy 9: January-July, 1994 We have acquired multi-wavelength images of Comet P/Shoemaker-Levy 9 from January-July using three telesopes for seven observing runs in order to monitor the brightness of the fragments, the dust tails, trails, and debris fan. Wide-field (FOV = 1 degree^2) CCD images with UBVRI filters were acquired with the 0.6m Schmidt telescopes at Kitt Peak National Observatory (KPNO) February, April, and June, 1994 and Cerro Tololo Interamerican Observatory (CTIO) in March and June, 1994. Moderate-field (FOV=1 arcmin^2) near-infrared images with J and K filters were acquired with the 3m NASA-Infrared Telescope Facility at Mauna Kea in January, May, and July, 1994. The 256 x 256 InSb array camera, NSFCam was used at the IRTF. The brightness of the nuclei are in the range 20- 21 magnitudes/arcsec^2. The data will be analyzed for temporal brightness variations of the nuclei, tails, dust trails, and debris fan. Comparison with the colors of the Sun, comets McNaught-Russell (1993v), Takamizawa-Levy (1994f) and asteroid 23 Thalia, also observed with this equipment, will be made. We anticipate finding evidence of ice grains that can be seen using broad-band visible and near-IR imaging although if icy grains and dust are intimately mixed, these observations may not be an appropriate diagnostic of water ice. This work was supported by NSF and NASA. 01.20-P Chodas P. W. Yeomans D. K. Comet Shoemaker-Levy 9 Impact Times and Impact Geometries The fragments of Comet Shoemaker-Levy 9 impacted Jupiter July 16-22, 1994, within 10 minutes of the final predicted impact times. Post-impact estimates of the impact times appear in the table below. These estimates are based upon direct observations by the Galileo spacecraft (for fragments H, K, L, and W), the times at which the Hubble Space Telescope observed impact plumes, the times at which infrared flashes were observed from the ground, the longitudes of impact features seen in HST images, and the relative impact times predicted from astrometry. The table also gives l-sigma uncertainties in minutes. Fragment Impact Time Fragment Impact Time (UT) (UT) A July 16 20:11 +/-3 N July 20 10:31 +/-4 B July 17 02:50 +/-6 P2 July 20 15:23 +/-7 C July l7 07:12 +/-4 Q2 July 20 19:44 +/-6 D July 17 11:54 +/-3 Ql July 20 20:13 +/-3 E July 17 15:11 +/-3 R July 21 05:33 +/-3 F July 18 00:33 +/-5 S July 21 15:15 +/-5 G July 18 07:32 _+/-2 T July 21 18:10 +/-7 H July 18 19:32 +/-1 U July 21 21:55 +/-7 K July 19 10:24 +/-1 V July 22 04:22 +/-5 L July 19 22:16 +/-1 W July 22 08:06 +/-1 The impacts occurred on the night side of the planet near the morning terminator, varying from 9 degrees past the limb as seen from the Earth for fragment A to 4 degrees for W. Fragment W passed behind Jupiter's limb only 5 seconds before impact, at an altitude of only 200 km above the l-bar level. The Jovicentric latitudes of the impacts ranged from 43.1 degrees S for fragment A to 44.2 degrees S for W. The longitudes of the impacts relative to the midnight meridian varied more widely, from 64 degrees to 71 degrees. The velocity of the fragments at impact was about 61 km/s, the incidence angle was about 43 degrees, and the azimuth angle of the velocity vector was about 15 degrees west of north. The time required for Jupiter's rotation to bring the impact sites into Earth view varied from 19 minutes for A to 9 minutes for W. 01.21-P Asphaug E. Benz W. Size and Density of Comet Shoemaker-Levy 9 Deduced by Modelling Break-up of the Parent 'Rubble Pile' The fragments of comet Shoemaker-Levy 9 produced a display more spectacular than many dared to hope; equally surprising was the wide variation in impact magnitude. In our prediction paper [1], a heterogeneous chain of "rubble swarms" is created when a parent comet with bulk density about 0.7 g/cc and grain density about 0.9 g/cc suffers tidal disruption and self-gravitational reaccretion along the 1992 perijove trajectory. Higher density parents reaccrete into one dominant clump, and parents with bulk density about 0.5 g/cc form about 20 clumps of nearly equal mass. We can explain the uniform crater chains on Ganymede and Callisto and the recent impacts into Jupiter by the same mechanism if the bulk density of comets is 0.6 +/- 0.1 g/cc, with SL-9 slightly denser than average. Many rejected this idea as soon as the first bolide struck, claiming that strength was needed to penetrate the deep atmosphere -- in spite of the fact that models predicting deep penetration [2] did not generally include strength. Spectroscopic evidence eventually showed that the impacts were, after all, quite shallow, bursting near the 1 bar level. It was also claimed, in spite of calculations to the contrary [3], that Jupiter's tide would disperse a strengthless bolide prior to atmospheric entry. This is also not true. The final issue concerns the size of the parent comet. Huge impact scars might seem to require very large impactors, yet three models including our own [1,4,5] conclude that the parent comet diameter was less than 2 km. We must strive to understand how a comparatively small mass creates such a big blemish. A typical rubble-swarm in our model is over 10 km in diameter before the final encounter with Jupiter, with a loosely-packed (approximately 0.1 g/cc) "core" about 1 km across. These approximately 10^14 g swarms each deposit approximately 2x10^27 ergs. While the core can be treated as a single entity in airburst models, the outer swarm must be treated as many independent impactors. A 1 km 0.1 g/cc bolide explodes near the one bar level [6], whereas a 100 m approximately 1 g/cc grain explodes about 100 km higher, two seconds earlier. Hundreds of smaller bursts, each depositing 10 to 100 Mt over a wide area before the approximately 3 Gt explosion of the central bolide, could play an important role in fireball and plume evolution. [1] Asphaug, E. and Benz, W., Nature 370 1994. [2] Takata, T. et al., Icarus, in press. [3] Yanagisawa, M. and Konno, T., LPSC XXV 1994. [4] Solum, J.C., Nature 370 1994. [5] Scotti, J.V. and Melosh, H.J., Nature 365 1993. [6] Zahnle, K. and Mac Low, M. M., Icarus 1994. 01.22-P Barker E. S. Cochran W. D. Cochran A. L. Na C. Pryor W. Baines K. H. Briley M. Smith V. Spectrophotometry and High-Dispersion Spectroscopy of Jupiter's Southern Latititudes During the Impact Period We report on visible spectrophotometry and high dispersion spectroscopy taken of Jupiter during the impact period (17 July - 23 July 1994 UT). Spectrophotometric observations were obtained using the longslit CCD spectrograph (ES2) on the 2.1m telescope to cover the 0.55 to 1.08 micron wavelength range. A seeing limited spatial resolution of about 1- 2 arcsec was achieved resulting in a spectral resolution of about 10 angstrom. The spectrograph slit was rotated to allow spatial sampling along and adjacent to the impact latitude (-44 degrees S). This scenario allowed sampling of impact regions and unperturbed regions as functions of both time and location. Spectrophotometric calibration of the low resolution dataset via standard stars and solar analogs will be used to provide absolute calibration of the narrow-band CCD images taken concurrently in the 6190 angstrom and 8930 angstrom CH4 bands by the McDonald Team on the 0.76m telescope (see adjacent poster paper) . The high resolution spectroscopy was done on the 2.7m telescope with a cross-dispersed echelle spectrograph, giving nearly complete spectral coverage between 0.40 and 1.05 microns. The coude slit was 1.2 x 8.1 arcsec permitting spatial resolution of the impact latitude in either a N-S or E-W direction. An R=60,000 allowed resolution of individual rotational CH4 lines in the impact region spectra. We will report on changes in the morphology of the continuum and the CH4 bands between 0.6 and 1.0 microns. For example, the observed impact regions appeared as bright features only in the strongest CH4 absorption regions within the 8930 angstrom band and conversely as dark features in the weaker absorption regions. Both the low- and high- dispersion spectra covered a range of CH4 band or line strengths which will aid in the determination of the altitude distribution of the condensates formed as a result of the impacts. 01.23-P Cochran A. L. Baines K. H. Barker Barker E. S. Cochran W. D. Frueh M. Kim S. Kim Y. Kudari A. Lester D. F. Na C. Pryor W. Gyorgyey Ries J. Trafton L. Whipple A. L. Wiant J. A Synopsis of McDonald Observatory Imaging Observations of Jupiter Before, During, and After the Shoemaker-Levy 9 Impact We report on optical CCD and IR images of Jupiter which were obtained at McDonald prior to the impacts of Shoemaker-Levy 9, during impacts, about one week following the last impact, and almost one month after the last impact. The CCD observations were obtained through narrow-band filters which isolate the 6190 and 8900 Angstrom CH4 bands and the adjacent continuum regions at 6040, 7640 and 8290 Angstrom. A barlow lens was utilized to expand the image on the chip so that Jupiter mostly filled the chip. The CCD observations before the impacts were obtained on the 0.9-m telescope, while the CCD observations during and after the impacts were obtained with the 0.8-m telescope. During the impacts and the following time, we obtained at least some data on each of 15 "nights" (we started observing as early as 4pm). The IR images were obtained on the 2.7-m telescope using a NICMOS3 array (Rokcam) with filters to isolate the 1.5 micrometer NH3 band, the 2.3 micrometer CH4 band, the 2.12 micrometer H2 S(0) pressure induced dipole absorption and the continuum at 1.58 micrometer and short K-band. Rokcam observations were obtained on 11 nights during and following the impacts. In addition to the CCD and Rokcam observations, we obtained about 14 hours of real-time video observations using the Lunar Laser Ranging 0.8-m telescope. In the course of our observations, we observed the flash associated with the impact of fragment R. Observations were obtained during several other impact periods but no flashes were detected. We compare images of the planet obtained with the CCD and Rokcam, including a movie in some wavelengths. We also show a time sequence of certain longitudes of Jupiter. Cross-cuts of the images for different wavelengths are compared to show how the morphology of the spots, bands, etc. change with latitude and wavelength. 01.24-P Lupishko D. F. The Results of the Ukraine Observation Program of Shoemaker-Levy 9 Collision with Jupiter The photometric, polarimetric, spectral, photographic and radio observations of Jupiter before, during and after the collision are carried out at the observatories of Ukraine, Middle Asia and Northern Caucasus. The spatial and time variations of polarization characteristics of atmosphere aerosol, the photometric profiles and the moments of flashes in Jupiter atmosphere, the changes in the structure of atmosphere cloud layer, the data on the state of Jupiter magnetosphere during the collision and Jupiter photographs of high spatial resolution (0.3 - 0.5 arc sec)are supposed to be obtained. All the results are going to be reported. This work was supported by grant of National Space Agency of Ukraine. 01.25-P Kleshchonok V. V. Churyumov K. I. Photoelectric Observations of Io and Europa in the Course of Fall Down of Secondary Nuclei A, H, Q2, Q1 and T of Comet D/SL-9 on to Jupiter Observations of the Jupiter satellites within the program for investigation of the comet D/SL-9 - Jupiter collision were held with the electrophotometer installed on the AZT-14 (D=0.5m) telescope at the Lesniki station of the Kiev University Astronomical Observatory. The electrophotometer worked in the regime of photon counting with registration on the PC IBM. In the course of observations standard UBVR filters were used. Temporal control tie was hand-made according to exact signals time. Circumstances for observations did not reveal changes in the satellites brightnesses which could be linked with reflection of light of fireball in the Jupiter atmosphere, with the exception of the nucleus fall down Q2. Here, two events that can be tied with the outburst during the nucleus fall down were found out. The first event has the following parameters: filter B, the outset of the outburst at 19:32:09 UT, continuity of the outburst 2.7 sec, the amplitude 0.12 mag [l]. Parameters of the second event: filter B, the outset at 19:48:10 UT, the continuity - 1.0 sec, the amplitude 0.11 mag. The second flash seems more probable both in continuity and it being close to the predicted time of the nucleus fall down Q2 on to Jupiter [2]. 1. Churyumov K.I. Io brightens. The Siderial Times, 1994, No. 10, p.5, IAU XXIInd General Assembly, The Hague. 2. Yeomans D.K., Chodas P.W. Comet SL-9 impact times. Interoff. memorand., 1994, 314.10-87. 01.26-P Larson S. Scotti J. Howell E. Marcialis R. Nolan M. Winsiewski W. A'Hearn M. Wellnitz D. Campins H. Rabinowitz D. Butner H. Tapia S. Vilas F. Doherty P. Bessell M. Brosch N. Liebowitz E. Gilmore A. Kervin P. Africano J. Levine S. Schuster W. Martin P. Verveer A. Moreno F. Molina A. Rutten R. Kidger M. The Comet Impact Network Experiment (CINE) The Comet Impact Network Experiment (CINE), an international collaboration designed to observe phenomena associated with the impact of Comet Shoemaker-Levy 9 with Jupiter was successfully deployed at the 4.2-m WHT at La Palma, Spain; the 2.5-m at Las Campanas, Chile; the 1.5- m at San Pedro Martir, Mexico; the 1.2-m of the Air Force Maui Optical Station, Hawaii; the 1.0-m at Mt. John Obs., New Zealand; the 1.0-m at Siding Spring Obs., Australia; the 0.6-m telescope at Perth Obs., Australia; a 1.0-m Air Force GEODSS telescope on Diego Garcia; and the 1.0-m telescope at the Wise Obs., Israel. Coronagraphic/spectrographic transfer optics were constructed to reduce the scattered light from Jupiter and normalize plates scales with the various facility CCD cameras. The main objectives were to 1) provide astrometric positions of the nuclei just prior to impact, 2) look for evidence of cometary particle fragmentation as the comet enters the Jovian magnetic field, 3) look for evidence of further breakup as the comet crosses its Roche limit, 4) obtain time-resolved spectra of the meteor flashes reflected off the satellites, 5) look for evidence of material ejected from the impact, 6) observe changes in the Jovian cloud morphology, and 7) look for evidence of dust capture and interaction with the Jovian ring. The project was implemented through the local observer-collaborators who applied for telescope time and provided the technical information needed to interface the coronagraphs with the telescopes and CCDs, and observers who accompanied the coronagraphs to the sites. This project was supported by the NASA Planetary Astronomy Program, the USAF Space Command and the various host institutions. 01.27-P Wellnitz D. D. A'Hearn M. F. Martin R. Comet SL9 Interactions with Jupiter as Observed from Perth, Australia The results of planned observations of the interactions of Comet Shoemaker-Levy 9 with Jupiter, using the University of Maryland CCD Imaging System for Comets (CISCo) on the Lowell Telescope at the Perth Observatory in Western Australia, will be reported. Planned observations include coronographic imaging of the cometary fragments as they approach and impact Jupiter, fast CCD imaging of satellites of Jupiter near the predicted times of cometary fragment impacts, imaging of the atmospheric fireball if it rises above the limb of Jupiter, coronographic imaging of the Jovian ring to observe the interaction of the cometary dust tail with the ring, imaging of Jupiter with various filters in the continuum and in methane absorption bands of various depths to search for cloud formation in the stratosphere after the fireball starts to cool, and low-resolution spectrographic imaging of Jupiter to search for changes in the absorption features in appropriate areas of Jupiter. This work is being supported by NASA and NSF funds. 01.28-P Jockers K. Observations of Jupiter's Atmosphere in the K-Band During the Shoemaker-Levy 9 Encounter Using ESO's infrared camera IRAC2B at the German/ESO 2.2m telescope at La Silla, Chile, observations of Jupiter's atmosphere were performed from July 16 to 24, 1994 (8 nights). The IRAC2B camera employs a NICMOS- 3 array with 256 x 256 pixel of a size of 40 microns. A scale of 0.27 arcsec pixel^-l was used. Regrettably not a single impact was observed. Filter images were taken through two interference filters with center wavelengths 2.105 and 2.365 microns, and FWHM 0.037 and .088 microns respectively. These wavelengths are located at the flank and in the centre of a deep methane absorption band. While at 2.105 microns some of the Jovian clouds are still visible, Jupiter's disk is practically black at 2.365 microns and even the Great Red Spot, which extends to great height, is barely visible. In both filters the impact clouds appear in emission and have about the same brightness. This indicates that the clouds must be located at atmospheric heights unaffected by methane absorption. They are remarkably stable but in the course of a few days are getting sheared by Jupiter's velocity field. Narrow-band images of spectral resolution approximately equal to 1000 were obtained with an imaging Fabry-Perot-Interferometer in the "hot" band of H(sub)3^+ at 2.093 microns and in the H2 quadrupole line at 2.121 microns. Both lines are sensitive to temperature enhancement in the outer layers of the Jovian atmosphere. Usually the "hot" band of H(sub)3^+ can be observed only when the auroral heating is particularly strong. Quick look data show no evidence for the presence of the emissions. The paper will present the time evolution of the impact clouds as observed with the interference filters. In addition we will provide evidence for the detection or non-detection of tlle H(sub)3^+ and H2 quadrupole line in tlle interferograms. 01.29-P Klavetter J. J. Petmecky S. Levine S. Near-IR Reflection Observations of the Shoemaker-Levy 9 Fireballs We observed the SL9 impacts into Jupiter from the San Pedro Martir Observatory (SPMO), administered by the Observatorio Astronmica Nacional (OAN) located in Baja, Mexico. This presentation will concentrate on the near IR observations made from the 2.1 meter telescope using the Camila IR imager. We will report on the dramatic impact spots/plumes observed from the SPMO/OAN site, including the L and R (and perhaps M and W) fragments. We will show the dramatic increase in brightness from our time series imaging, including photometry of the spots/plumes. The morphology of the spots is dramatically different at the wavelengths observed, from 1.1 microns to 2.3 microns, with the spots being essentially invisible at the smaller wavelength bands. We will show images from filters throughout this range and place temperature limits on the thermal continuum radiation observed. 01.30-P Wasserman L. H. Buie M. W. Millis R. L. Imaging of Shoemaker-Levy 9 Impact Phenomena from Northeastern Australia We will be conducting imaging observations of the Shoemaker-Levy 9 impact on Jupiter from Northeastern Austrailia from 1994 July 12-25. Our observations will be made with our portable Celestron 14" telescope with the Occultation CCD camera system that was presented at last year's DPS meeting. The system has now been retro-fitted with an automated 10 position filter wheel and a new optical mode for an image scale of approximately 0.5"/pix. Our two primary goals are (1) to take extensive sets if images to monitor the Jovian atmosphere for any changes caused by the impacts, and (2) to attempt to observe the flashes from the impacts in reflection off of a well-placed satellite. Current predictions indicate that from our location, four impact occur in darkness. One of these is the only impact that occurs with Europa in eclipse where a flash may be seen. Our system can quickly cycle through the filter set for multi-spectral imaging of Jupiter. At the time of fragment impacts, we can quickly re- configure and take high-frame rate data (up to 5 Hz) for the flashes. We have also developed a spectroscopic mode that can be used to derive the color temperature evolution of the prompt flash, provided enough signal is generated from the impacts. We will present results from our efforts and will provide a catalog of the dataset for interested people. This work was funded by NSF grant AST-9322449. 01.31-P Lazzaro D. Moreira J. K. Foryta D. W. P/Shoemaker-Levy 9 Impact: Observations at the Pico-dos-Dias Observatory We report the observations planned at the Observatorio do Pico-dos-Dias (Itajuba, Brazil) for the impact on Jupiter of comet Shoemaker-Levy 9 (SL9) expected to occur on July 94 (Marsden, 1993, IAU Circular No. 5801; S Green, 1993, IAU Circular No. 5807). Since the impact of the 20-22 fragments of SL9 are expected to take place on the side of Jupiter away from the Earth, we plan to observe the reflected light of the bolide and/or fireball, subsequent to each impact, from a suitably placed Galilean satellite. A rapid photometer mounted on a 60cm telescope will probably be able to detect these phenomena using an integration time of 0.1 seg. With this instrument we expect an impact detectability limit of 14.5 to 12.5 magnitudes (V), whether or not the observed satellite is in eclipse. Assuming a luminosity efficiency of 3% we estimate that the above magnitudes correspond to a fragment diameter of 100-200m. A lower luminosity efficiency will necessarily increase these diameters up to 1- 2 km, which would be just the greatest fragments. The final aim of these observations is the obtention of some data relevant to determine the fragment distribution of SL9. We pretend, by the time of the meeting, to carry out at least preliminary reductions in order to deduce the size of the fragments from the observed signals (if any!!). 01.32-P Glenar D. A. Hillman J. J. Le Louarn M. Drummond J. D. Narrow-band Visible and IR Imagery of Jupiter During the Comet Shoemaker/Levy-9 Collision Series We observed the Southern hemisphere of Jupiter on several nights during the Jupiter SL/9 impact sequence, using the Coude focus at the Kirtland Air Force Base, 1.5-meter adaptive optics telescope. The objectives were to identify condensed volatiles in the high atmosphere at the locations of the impact sites, track the motions of these sites as they transit the disk, and examine their breakup. Multispectral images were acquired in the CH4 bands at 725 and 890 nm, the NH3 bands at 645 and 790 nm and in their adjacent continua using a tunable acousto-optic imaging spectrometer and silicon CCD at the focal plane, with a spectral resolution (Lambda/Delta Lambda) of 380 to 530. The stratosphere near 10 mbar was simultaneously sounded by imaging in the deep 2.35 micrometer CH4 band using a NICMOS-3 camera with cooled narrow band filter. All observations were photometrically calibrated and reduced to absolute reflectivity (I/F) using close coincidence standard stars and published solar intensities. A summary of the major results is presented. This work was supported by the NASA Planetary Instrument Definition and Development Program and the GSFC Directors Discretionary Fund. 01.33-P Woodney L. M. Meier R. A'Hearn M. F. Wellnitz D. Smith T. High-speed Photometry of the Jovian Satellites During Comet P/Shoemaker-Levy 9's Impact with Jupiter At Mt. Singleton, West Australia, a high-speed photometer and a 14 inch Celestron were used to look for flashes off Io or Europa during the expected impact times of D, E, K, and N. The observations were made in broad-band white light. Io was well monitored during the impact time of D and no flashes are apparent. There is a possible effect at the time of impact of E, but due to problems with tracking caused by high winds, we can not yet rule out contamination from Jupiter in the aperture. Comparison with results from other observers may resolve this uncertainty. No flashes were observed for the impact of fragment K, which occurred while Europa was in eclipse, or for fragment N. The brightness of the monitored satellites changed by less than approximately 10%. Careful analysis should allow us to look for small effects and better constrain upper limits. 01.34-P Stuwe J. A. Schulz R. Encrenaz Th. A'Hearn M. F. Shoemaker-Levy 9 and Its Impact sites on Jupiter We report on observations in the visible spectral range of P/Shoemaker- Levy 9 before and Jupiter after the impact. SL-9 was observed with the ESO Multi Mode Instrument (EMMI) at the 3.5-m New-Technology-Telescope (NTT) at La Silla, Chile, on July 1 and 2, 1994, two weeks before its impact on Jupiter. Highly resolved images of the entire cometary train were obtained in B, V, R, and I. A comparative study of the individual fragments in terms of color, brightness and morphological appearance will be presented. Due to the large field of view of the instrument all fragments could be imaged in one frame. The comparison of the individual fragments relative to each other is therefore not affected by errors due to changing observational conditions. The large spatial scale (approximately equal to 1200 km pixel^-1) on the other hand allows the detailed analysis of the dust distribution around the individual sub- nuclei. The dust distribution around some fragments appears to be elongated slightly towards the direction of Jupiter. Additionally, we obtained long-slit spectrophotometric observations of SL-9 on both dates using EMMI in the dichroic medium dispersion mode (DIMD), which allowed the parallel use of a blue- and a red-sensitive CCD covering a spectral range of 3200 angstrom less than lambda less than 10400 angstrom (3.5 angstrom pixel^-l). The slit was aligned along the cometary train from fragment K to fragment S. The spectra of fragments K, L, P, Q, and S were searched for the CN (0-0) emission band at 3875 angstrom. No CN emission feature was detected for either fragment and we therefore present 3-sigma upper limits on the CN production rates. After the impact Jupiter was imaged on two nights (July 23/24 and 25/26, 1994) with the NTT and the Superb Seeing Imager (SUSI) in six different filters to study the appearance of the impact sites in different spectral ranges. The time difference of two days (approximately 5 Jupiter rotations) between both observational series also allows the investigation of the temporal evolution of the impact sites. 01.35-P Rogers J. H. Jupiter's Visible Clouds Following the Comet Impacts Imaging and visual observations of Jupiter after the comet impacts showed extremely dark spots, which were the darkest features on the planet and in some cases grew larger than the Great Red Spot. The size of each visible 'scar' was roughly in proportion to the reported magnitude of the fireball. The scars always appeared at least as dark near the limb as when fully on the disk. For example, sites H and Q1 were observed coming onto the disk one hour after the impacts, and became darker on subsequent days, with an apparently black core. There were no systematic motions (less than ten degrees per month) relative to the S.S.S. Temperate Current or System III. There was evidence for diverse local motions, viz: increase then decrease in longitude of site E; eastward and westward expansion of site K/W; northward extension of site H. Most sites have lasted over a month, although site A disappeared within 2 weeks. Most sites were beginning to fade after 10-20 days, while grey patches were appearing outside the previous boundaries of some sites. By late August, sites A and C had disappeared, and sites Q1, H, and E were reduced to indistinct condensations on a dusky belt which extended all round the planet at the impact latitude. The three largest complexes -- K/W, L, and D/G/S -- were still very large and dark in late August but had changed shape; dark material had spread for tens of degrees preceding the original boundaries of K/W and L. Before the impacts, five dark patches around 40 deg.S had been tracked in the S.S. Temperate Current. They appear to be part of compensatory changes south of the STB following its revival in 1993. These dark patches remained visible as the impact sites faded. This report is the result of observations by amateur observers in several countries, especially: F. Balella (Italy), M. Bosselaers and colleagues (Belgium), D. Bruton and R. Schmude (USA), R. Bullen (UK), E. Colombo (Italy), P. Devadas and Mrs. Komala (India), M. Foulkes (UK), H. Gross (Germany), C. Hernandez (USA), J. Lancashire (UK), R.J. McKim (USA), H-J. Mettig (Germany), H. Miles (UK), I. Miyazaki (Japan), T. Platt (UK), J. Rogers (UK), G. Teichert (France), D. Troiani (USA), J. Warell (Sweden). 01.36-P Phillips C. B. Mueller B. E. A. Broad-Band CCD Photometry of Jupiter's Impact Scars Observations of Comet P/Shoemaker-Levy 9's impact on Jupiter were made using the 36-inch telescope on Kitt Peak on July 20 and 22 (UT), during the impacts, and on August 3 (UT) as a follow-up night. Images were taken using a Harris UBVRI filter set and a 3.5 magnitude neutral density filter, which was placed directly in front of the filter wheel. The telescope was set to f/13.5 which resulted in a resolution of 0.384"/pixel, and the images clearly show the dark impact scars. Preliminary analysis has resulted in color composites which show both structure within the spots, and changes in color due to the spots' aging between the July and August observation dates, as the August follow-up date was chosen to include the same rotational phase of Jupiter. We are also obtaining relative photometry of the impact scars in relation to Jupiter's Galilean satellites and the undisturbed northern hemisphere of the planet. We hope to trace the brightness evolution of the spots to provide a quantitative counterpart to the qualitative visual spreading of the impact scars during the two weeks spanned by our observations. 01.37-P Moreno F. Molina A. Ortiz J. L. Munoz O. Kidger M. del Rosario J. C. Larson S. Campins H. Consequences of the Comet Shoemaker-Levy 9 Impact on the Jovian Atmosphere from UV to Near-Infrared Imagery The impact sites of the fragments of the comet Shoemaker-Levy 9 in the Jovian atmosphere were studied at UV through near-infrared imagery at various telescopes in Spain. Prior to the impact sequence, systematic observations were obtained in order to get a Jovian atmospheric reference. Methane band imaging at the center of the absorption features of different strengths will help to study the height dependence in the aerosol content and dynamic properties of the stratosphere. Particularly, we present here some preliminary results from CCD images obtained using the 4.2 m William Herschel Telescope at La Palma. These images were obtained during very good sky conditions and sub-arcsec resolution on 16-22nd of July. Low and high resolution (0.34 Angstrom/pixel) spectra were also obtained with the WHT using the ISIS spectrograph. These observations have been made as a part of the Comet Impact Network Experiment. 01.38-P McGhee C. Gierasch P. Goodman J. Hayward T. Moersch J. Nicholson P. Squyres S. Van Cleve J. Matthews K. Neugebauer G. Weinberger A. Orton G. Observations of the Shoemaker-Levy 9 Impacts from Palomar Using the 256 x 256 InSb Camera We observed the effects on the jovian atmosphere of the collision of comet Shoemaker-Levy 9 in July and August 1994, using near-infrared imaging at the Palomar 200-inch with the Caltech near-IR Cassegrain camera. This camera permits imaging through broadband J, H, K, or L' filters, or two narrowband (R = lambda/delta lambda about 70) circular variable filters tunable between 1.5 and 5.2 microns. Our observations focussed on the spatial distribution and temporal evolution of the impact sites, and their near-infrared spectral characteristics. Observations were made from 15-27 July UT and from August 16-19 and 28- 29. On each night after July 21, several complete sequences of broadband and narrowband images at 17 selected wavelengths in the 2.0-2.4 micron and 3.0-4.0 micron regions were obtained. In narrowband images of Jupiter in the strong methane bands at 2.2-2.4 microns and 3.2-3.5 microns the reflected light from the main tropospheric cloud deck is almost competely suppressed, revealing the signatures of the stratospheric hazes. Observations at 2.0-2.35 microns of the increasing strength of the CH4 absorptions provide an altitude estimate of about 10 mb for these hazes. The 2.3 micron images from July 24-25, August 17-19, and August 28-29 have been assembled into mosaics which show the complete distribution of the impact hazes as well as their temporal evolution. The longitudes of nine distinct features, associated with impacts G, R, Q1, H, E, A, C, K and L have been measured in the July data, and found to be consistent (within 3 degrees) with impact site longitudes reported by Ingersoll et al. from HST images. With the exception of R, all features remain identifiable in the August data, albeit considerably altered in shape and size. By late August, sites G, H, and E extended over about 20 degrees in longitude, while Q1, C, K and L retained compact cores. These well-defined features show a mean eastward drift relative to System III of about 13 degrees over 24 days, or 5.5 ms^-1. The more diffuse structures appear to map the zonal wind profile in the middle stratosphere. This work was supported by a grant from the NASA Planetary Astronomy program. 01.39-P Foust J. A. Hammel H. B. Elliot J. L. Meech K. J. Patten B. M. Observations of the Impact of Comet Shoemaker-Levy 9 Using a High-Speed CCD Camera Although the fragments of comet Shoemaker-Levy 9 impacted on the far side of Jupiter as seen from Earth, two phenomena associated with the impact events were postulated to be visible: the impact flash, reflected off an appropriately placed satellite such as Io; and a plume or fireball from the impact site that rises beyond the Jovian limb and into direct view from Earth. Both of these phenomena require observations with high time resolution and accurate timing to provide details on the depth and magnitude of the explosions. We observed the impacts and Jupiter using a high-speed CCD camera mounted on the University of Hawaii Planetary Patrol 0.61-m telescope at Mauna Kea Observatory. This system is capable of taking five or more images per second over a small field and utilizes a Global Positioning Satellite (GPS) receiver to provide accurate timing, making this an ideal system to carry out observations of impact flashes and plumes. Of the four impacts potentially visible from Mauna Kea, weather conditions permitted us to observe two, impacts C and R. High-speed imaging of Io, Europa, and Ganymede during the time of impact C showed no visible change in the R band brightness of the satellites. High-speed imaging of the limb of Jupiter in B band during impact R showed no strong signal for a plume or fireball at visible wavelengths. A more thorough analysis of the observations is being conducted to look for small (order approximately 1%) brightness variations and set upper limits on the brightness of the impact effects at visible wavelengths. 01.40-P Drossart P. Barucci A. Colas F. Crovisier J. Fulchignoni M. Lecacheux J. Roos-Serote M. Roques F. Observations of Jupiter at Pic-du-Midi During the SL9 Impacts Period Observations of Jupiter have been conducted at Pic-du-Midi, first at the 2 meter Bernard Lyot telescope with the spectrometer MU-SICOS, working in the red part of the visible spectrum between 540-880 nm at a spectral resolving power of 38000, second on the 1 meter telescope with the CCD imaging system Astriane, working in the visible and the near infrared (J-H-K filters). The main results are: (1) Several emission lines have been detected on impacts L and Ql in spectra taken on July 19 at 22:42 UT (impact L) and on July 20 at 20:24 UT (impact Ql). The strongest lines are the Na doublet at 589.0 and 589.6 nm . Other detected lines, not present in Jupiter spectra before impacts are due to Li (670.8 nm), K (766.5 nm), Ca (657.3 nm) and H alpha (656.3 nm). These lines are observed in spectra less than 30 min after impact and disappear totally in less than 1 hour after impact. (2) CCD images show the evolution of the impact sites at several time scales. Images in K filter show the complete sequence of the impacts, in particular, impacts H, L and Ql. A flash appears first at the limb, which is observed in all the bands (J-H-K). Then, a bright emission feature appears in filter K, which should correspond to the raise of the plume in the high atmosphere of Jupiter, slowly decreasing. In the long term, the evolution of the dark cloud is followed in various filters in the visible (including interferential methane filter). These images will be reduced to provide the albedo of the dark clouds in standard photometric filters. 01.41-P Gehrels T. Scotti J. V. Spacewatch Observations and Astrometry of P/Shoemaker-Levy 9 Observations were made up to the time of impact, mostly with the Spacewatch Telescope which is the 0.9-m Newtonian Reflector of the Steward Observatory on Kitt Peak. The astrometry was used for the orbit and impact predictions. Size estimates are being updated; ours are smaller than generally used in the modelling. 01.42-P Lambert J. V. Africano J. L. Nishimoto D. L. Nolan R. A. Kervin P. Medrano R. Five Micron Observations of the Comet Shoemaker-Levy 9 Jupiter C, F, and R Impacts from the Air Force Maui Optical Station (AMOS) Near infrared, 4.8 - 5.05 micron, imagery of the C, F, and R fragment impacts of Comet Shoemaker-Levy 9 on Jupiter was collected using the Enhanced Longwave Spectrometer/Imager (ELSI) on the 1.6-meter AMOS telescope at the Air Force Maui Optical Station. The impact sites were visible only after they reached the planet's limb, then faded rapidly, within ten minutes, leaving persistent spots slightly brighter than the surrounding area. These spots appeared to lag the corresponding dark impact spots observed in visible imagery recorded using the 1.2-meter MOTIF telescope by ten to fifteen degrees in rotation. Extensive visible and infrared observations were also made during the periods between observable impacts. Several northern hemisphere spots and other structures not apparent in the pre-impact five micron imagery were observed. Five micron light curves for the impacts and infrared and visible imagery will be presented. A relative intensity light curve for the R-fragment impact is plotted and available in hard copy. 01.43-P Olson K. M. Mumma M. J. Simulations of the Breakup and Dynamical Evolution of Comet Shoemaker/Levy 9 Employing a Swarm Model We investigated the dynamical evolution of a swarm of fragments produced by tidal disruption of the nucleus of comet Shoemaker-Levy 9, for comparison with observed properties of the nuclear train. We take the initial state of Ihe comet nucleus to be a loose agglomeration of macroscopic cometesimals, each bound more strongly internally than to each other. Tidal disruption of the nucleus near perijove then produces an initial swarm of these cometesimals (approximately 10^6 particles), with possibly one sizable core remaining. We performed gravitational N- body simulations of the subsequent dynamical evolution of this initial swarm, and explicitly accounted for collisions between swarm particles, gravitational interactions among them, and interaction with the tidal field of Jupiter. We used an N-body tree code designed for highly parallel computers, and ran a large number of simulations with particle numbers ranging from 16,384 up to 131,072. The volume filling factor of the pre-split nucleus was allowed to vary from 0.001-1.0. We find that the initial swarm is tidally stretched into an elongated structure which grows in length as the simulation proceeds. We also find that in ALL cases the swarm becomes gravitationally unstable and a number of clumps of bodies form. The time at which the instability sets in (relative to periJove), the number of clumps which form, and the nature of the clumps depend on assumptions about the detailed collisional process between bodies. When the pre-split nucleus is optimally packed (filling factor = 1) and the colliding particles are treated as hard spheres, the instability does not set in until 78 hours (approximately 41 Rj) after periJove. When the radius of each body is 0.5 of that in the optimally packed case, and some dissipation is added to the collisions, the initial swarm of particles is very unstable and distinct clumps form very soon after periJove (approximately 9 hrs, approximately 7.6 Rj). We have found no cases to date which were not unstable to some degree at some point in the simulation. In general, we find that a collection of gravitationally and collisionally interacting particles is gravitationally unstable as it passes through the tidal field of Jupiter for a large range of the parameters considered by our model. This tends to support the theory that comet Shoemaker-Levy 9 was initially fragmented into a large number (10^5 - 10^6) of small cometesimals and also has implications for the structure of comets in general. We find it difficult to draw detailed conclusions about the initial state of the comet before breakup owing to the fact that clumps of particles form for a large range of the free parameters of the model. These clumps are similar in number and spacing to the observed 'string of pearls' observed prior to impact with Jupiter. They explain in a simple way virtually all of the observed properties demonstrated by the 'fragments' up to and including disruption in the Jovian stratosphere. This work was supported by the NASA Planetary Astronomy Program RTOP 196-41-54 and by the NASA/ESS HPCC program. 01.44-P Tozzi G. P. Richichi A. Ferrara A. Calamai G. IR Photometric Observations of the Impact of Comet SL9 with Jupiter The impacts of fragments A, H, Q 1, Q2, T, and U of the comet Shoemaker- Levy 9 (1993e) with Jupiter have been observed in the IR with the 2.2m telescope of the Calar Alto Observatory. The sampling rate of the fast photometer was typically 100-500 Hz, thus allowing us to follow with high time resolution the evolution of the phenomena. The filters used were a broad band K (lambda(sub)0 = 2.20 microns, delta lambda = 0.47 micron), and a narrow band ice filter (lambda(sub)0 = 3.12 micron, delta lambda = 0.14 micron). The diaphragm was in all cases 15 arcsec. During impact A, we monitored the luminosity of Europa at K. No evidence of significant variations were revealed, within a dynamic range of 6-7 mag of the satellite's brightness (0.4%-0.1%). During all other events, we monitored directly Jupiter's disk, centering at the expected impact point. While no evidence of enhanced emission was revealed for the T and U impacts, the H and Q impacts gave origin to increases in luminosity which at the peak exceeded the emission of the planet's surface (in our diaphragm) by a factor of approximately 25 - 50. We present the corresponding lightcurves, which extend over about 0.5-1 hr with a (rebinned) resolution of 1 s. It is noteworthy that in both cases a small "precursor" event is seen, at approximately 1-2 minutes after the predicted and measured impact time and about 10 minutes before the actual development of the fireball. It is also interesting to note that while the Q1 fireball was extremely bright, the Q2 fireball apparently did not produce significant emission. Another interesting feature is the presence of a plateau in the decreasing part of the lightcurve, especially pronounced in the case of the H fireball. Comparison with other lightcurves taken at different wavelengths will be shown and possible interpretation will be given. 01.45-P Wiedemann G. Encrenaz Th. Schultz R. Stuewe J. A. Drossart P. Crovisier J. Near-Infrared Spectroscopy of Jupiter at the Time of SL9 Impact Near-IR spectra of Jupiter have been recorded with the IRSPEC imaging spectrometer at the 3.5m NTT (ESO, La Silla), with the 4.4 arcsec slit aligned along the parallel of impacts (latitude l= -44 degrees). After the last impact, spectra were also recorded in the Northern hemisphere at l=+44 degrees (see Schulz et al, this issue). Spectra were recorded around the H2 S(1) quadrupole line at 2.12 microns, and around the 3.533 micron H(sub)^+ line. Most of the impact sites (and later their images at l=+44 degrees) were easily detected at 2.12 microns. Shortly after the impacts, spectra recorded in the 2.107-2.135 micron range with a resolving power of 2000 show a drastic increase of the signal and a change in slope, with a maximum peaking toward shorter wavelengths. The simplest explanation is that there is a very strong scattering over a newly formed stratospheric haze. This strong component sometimes hides the H2 quadrupole line, which is detected when the continuum is low enough. These data are being analysed to derive information about the particle size and the stratospheric temperature at pressure levels of about 0.1-1 microbar. Emission lines of H(sub)3^+ were detected in the 3.501-3.566 micron range, with a resolving power of 1700, over many impact sites. As a general rule, these emissions were stronger over more evolved sites, as compared to the fresh impact sites. In the case of strongest emissions, the multiplet of H(sub)3^+ previously detected in auroral regions was observed, which will allow the determination of both the H(sub)3^+ column density and the stratospheric temperature around 10-100 nanobars. 01.46-P Xie X. Olson K. Mumma M. J. Constraints on the Masses and Sizes of SL9 Fragments We have performed N-body simulations of the infall of the fragments of comet Shoemaker/Levy 9 from apoJove to shortly before impact with Jupiter. These simulations assumed that each fragment is itself composed of a large number of small bodies (the swarm model). It was also assumed that the bodies interact solely through their self gravitational interactions and also with the tidal field of Jupiter. Collisions between the bodies have been ignored for this set of simulations. The swarm of bodies is assumed to be initially in vireal equilibrium at apoJove and then follows an orbit which will bring it into collision with Jupiter. For this study we have varied the swarm mass (10^l3 - 10^l5 gms) as well as its radii (10 -100 km) to determine for what range of these parameters the swarms hold together and would impact the surface of Jupiter as a more or less solid object. The simulations show that for the range of masses considered here and a critical size of approximately 10 km, the swarms remain bound up until a few days before impact. 01.47-P Reitsema H. J. Hubbard W. B. Roques F. Peyrot A. Vignand M. Coordinated Imaging of SL-9 Impact Events: Observations from Les Makes, La Reunion High time resolution photometric observations of impact events and imaging of impact sites were obtained from four globally-distributed distributed sites using similar CCD systems. We report here data obtained from Ile de La Reunion (at latitude -21:11:57, longitude E55:24:35, elevation 995 m) which complete the observing net which also included sites in Hawaii, Chile and Australia. Data were obtained each night from 15 July to 24 July with the 36 cm telescope of the Observatoire des Makes and seven filters covering B, V, R, and two methane bands and corresponding continuum bands. Impact events A, E, H, and S were observed with 0.4-sec time resolution during the impact times, while slower multi-wavelength image sequences were taken during impact events P, Q2, and T. Rapid image sequences of events A, E, and S were obtained in the methane 890 nm filter, while the rapid image sequence of event H was obtained using the B filter. However ongoing analyses of impact events have yet to show any discrete signal from any of these atmospheric entry events. Dark atmospheric disturbances and occasional bright methane features were imaged at impact locations. The poster will display representative images and data. Supported by NASA Grants NAGW-1555 and NAGW-4072. 01.48-P Max C. Gavel D. Johansson E. Bissinger H. An J. Lawrence T. Olivier S. Liu M. Bradford W. Impacts of Comet Shoemaker-Levy: Speckle Imaging in the Visible Using the 3 Meter Telescope at Lick Observatory We performed speckle imaging of the impacts of Comet Shoemaker-Levy 9 with Jupiter at the Lick Observatory 3 meter telescope, from July 19 through 22, 1994. Images were obtained at wavelengths of 0.55, 0.7, and 0.85 microns. Using exposure times of 200 - 300 msec, we are able to obtain high resolution images using a bispectral speckle reconstruction algorithm from 20 to 40 individual speckle frames. We were able to obtain continuous data over periods of 3 to 4 hours for several of the impact points, and have made time-lapse movies following the rotation and evolution of the impact spots. Features such as the dark "eyebrow" and the interior darker region of the impact points are clearly distinguished. In this presentation we shall show both images and videos of our speckle reconstructions, and shall present preliminary conclusions concerning the evolution of impact point structure over periods of hours to days. This research was supported by the US Department of Energy under contract No. E-7405-ENG-48 to the University of California, and by the Institute of Geophysics and Planetary Physics at LLNL. 01.49-P Lopez-Moreno J. J. Rodriguez J. Formisano V. CCD Images of the Shoemaker-Levy 9 Impacts on Jupiter from Sierra Nevada Observatory A continuous coverage with CCD observations has been performed by using the 1.52 telescope of the Sierra Nevada Observatory in Granada, Spain, during the week (16-22 July) of the SL9 impacts. The telescope was equipped with a direct CCD with filters and with a multispectral imaging system (VNIR) covering from 350 to 1005 nm. During this period a daily average of 50 CCD images during the 3 hours of visibility of Jupiter were taken. We have also made observations of the impact regions some days after the collisions (26, 27 and 29 July) in which the remaining of the impacts were still clearly visible. The CCD was equipped with 6 filters covering the visible spectrum from 426 to 829 nm. We present here some results on the evolution of the spot H from its first appearance (H0) in July 18 to its seven passage (H7) on July 21. We present ratio of the images at ammonia (648 nm) and methane (727 nm) bands to the one obtained in the continuum at 635 nm and make estimations of the depth of the features for each appearance. This work was supported by CICYT under grants ESP-93-0338 and ESP-1290- C02-01. SESSION 02 ....... Comet Shoemaker-Levy 9 II Monday, 10:30 - 12:00 Crystal Ballroom Reta Beebe and William B. Hubbard, Moderators 02.01 Noll K. S.* McGrath M. Weaver H. A. Atreya S. Caldwell J. J. Trafton L. Yelle R. Hubble Space Telescope Spectroscopic Observations of Jupiter After the Impact of Comet SL9 Dramatic changes in Jupiter's UV spectrum were recorded with Hubble Space Telescope's (HST) Faint Object Spectrograph (FOS) and High Resolution Spectrograph (HRS) following the impact of fragment G. Darkening at all wavelengths and absorption and emission from a wide variety of molecules and atoms were observed. In particular four different sulfur-containing molecules were identified in quantities that indicate the major source of sulfur is almost certainly Jupiter. This observation provides a constraint on the depth of penetration of the fragments and is also the first observation of sulfur in Jupiter. A ratio of an 18 July FOS spectrum of the G impact site 3 hours after impact to one obtained on 14 July effectively removes the solar spectrum and normal jovian absorptions. The ratio shows strong absorption bands of S2, CS2, and NH3; evidence for H2S is also present in the shape of the absorption near 210 nm. The estimated column abundance of S2, N about l0^l9 cm^-2 corresponds to a mass of sulfur of m similar to 10l4g in our 0.9 arcsec field of view. This lower limit is a significantly greater mass of sulfur than could be present in a l km diameter impactor. The second post-impact FOS spectrum was obtained on 21 July, approximately 30 minutes after the impact of fragment S. In this spectrum we identify all the molecules identified in the 18 July spectrum. In addition we observe strong, narrow emission lines from MgII, MgI, SiI, FeI, and CS. Lower limits for the abundances of the metal atoms are about l part in 10^6 of a l0^14 g impactor, easily consistent with expected abundances of these elements in the impactors. The remaining two FOS spectra obtained in August, on 9 August and 23 August, show an increase in NH3 relative to the CS2 absorption while the S2 is no longer detectable. We searched for Si- and 0- containing molecules in both EIRS and FOS spectra. Derived upper limits indicate that very little of either element is present in gas-phase species after the impacts. This evidence may constrain the initial elemental abundances of the impactor, i.e. SL9 may have been a low-volatile object. This research is supported by grant GO-5624.12-93A from the Space Telescope Science Institute. Significant contributions to this work were made by Paul Feldman, Chris Barnet, Diane Gilmore, Scott Edgington, Ed Smith, and by Alex Storrs, Andy Lubenow, David Taylor, and many others at STScI. 02.02 Yelle R. V. McGrath M. Noll K. Weaver H. Atreya S. Caldwell J. Trafton L. Spectroscopic Constraints on the Evolution of Sulfur-Bearing Molecules in the Jovian Atmosphere Ultraviolet spectroscopic observations of Jupiter's atmosphere subsequent to the impact of comet p/Shoemaker-Levy 9 (SL9) have detected the sulfur-bearing molecules S2, CS2, CS, and H2S. Several observations were carried out with the Hubble Space Telescope Faint Object Spectrograph (FOS) in the region from 170 to 330 nm with a spectral resolution of 0.4 nm. A spectrum from the G impact site obtained on 18 July 1994 has as its most prominent feature a series of absorption bands from 250-300 nm which are clearly due to the S2 (B-X) transition. In the 190-220 nm region this spectrum also contains absorption features due to CS2 as well as absorption features attributed to NH3 and H2S. Spectra obtained under similar viewing conditions on 9 and 24 August 1994 continue to show the NH3, CS2, and H2S absorption features but the S2 absorption is greatly reduced or absent. Spectra acquired from Jupiter's limb on 21 July 1994 show the absorption features mentioned above but also contain emission features due to CS and several metallic species. Noll et al. (this session) will present an overview of FOS results and implications. This presentation will focus on the ramifications of FOS spectroscopy on the post-impact evolution of the sulfur-bearing species. The observed changes in the spectra may be due to spatial inhomgeneities or temporal changes. In this talk we will explore the latter possibility. The S2 bands are the sulfur analogs of the O2 Schumann- Runge band system which plays a critical role in terrestrial atmospheric chemistry. Absorption in these S2 bands leads to production of atomic sulfur, which will react with ambient atmospheric species further altering the composition of the atmosphere. This research is supported by grant GO-5624.12-93A from the Space Telescope Science Institute. Significant contributions to this work were made by Paul Feldman, Chris Barnet, Diane Gilmore, Scott Edgington, and Ed Smith, and by Alex Storrs, Andy Lubenow, David Taylor, and many others at STScI. 02.03 Lellouch E.* Paubert G. Moreno R. Festou M. Bockelee-Morvan D. Colom P. Crovisier J. Encrenaz T. Gautier D. Marten A. Despois D. Strobel D. Millimeter-Wave Observations of the Jupiter/Comet Shoemaker-Levy 9 Collision from IRAM 30-m Telescope: CO, CS, and OCS Millimeter-wave observations of the collision of comet Shoemaker-Levy 9 with Jupiter were conducted at the IRAM 30-m telescope on July 17-28, 1994. These observations led to the detection of emission lines of CO at 230.538 GHz and CS at 244.935 GHz on a number of impact sites (C,E,G,H,K,L,Q+G for CO; K,L,Q+G,W for CS). The typical linewidth (FWHM) is 2 MHz, suggesting a primarily collisional broadening (with a probable contribution due to velocity smearing within the impact sites) and indicating a formation level of about 1 mbar. For a few sites, the lines were monitored over several days, providing information on their temporal evolution. Generally, the lines appear to be weak immediately after impact (0.1-0.2 K antenna temperature contrast), then to increase to reach a maximum (0.5-1 K) one or two days after impact, then to decrease. In particular, on impact site Q+G, the decay of the emissions from July 21 to July 23 and 25 was observed. On July 28, the CO and CS lines were detected in absorption, with perhaps an emission core in the case of CO. All these variations probably result from a combination of variations in (i) the horizontal extent of the sites (ii) the vertical distribution of the molecules and (iii) the temperature profile. We also report the probable detection of OCS at 218.903 GHz on impact site W on July 22, and upper limits on CO^+, CH3OH, HC3N, H2S, SO2, CN, and H2CO. Very preliminary modelling, assuming entire deposition/formation of the molecules near 1 mbar, suggests that the strongest CO and CS lines require approximately 10^14g of CO and 5 x 10^11g of CS. On impact site W, the lines indicate about 1.5 x 10^11g of CS and 1.5 x 10^12g of OCS. The corresponding relative abundances (in volume) for CS:OCS:CO are about 1:7:350. A cometary origin for the O and S seen in CO, CS, and OCS seems therefore plausible at the present stage. 02.04 Encrenaz Th.* Schulz R. Stuewe J. A. Wiedemann G. Drossart P. Crovisier J. Detection of 3.5 Micron CH4 emission at the Time of SL9-H Impact: An Estimate of Rotational Temperatures We have monitored Jupiter in the 3.501-3.566 micron range shortly after the impact of fragment H, using the IRSPEC imaging spectrometer at the 3.5m NTT (ESO, La Silla). The resolving power was 1700; the 4.4 arcsec slit was aligned along the parallel of impacts, and the pixel size along this axis was 2.2 arcsec. Our observations started on July 18, UT 19:46, i.e. 13 mn after the impact, at a rate of 1 image per minute. A very strong emission was detected over the whole spectral range, due to high J-value multiplets of the CH4 nu(sub)3 band (J=14 to J=18). The signal intensity decreased exponentially with a timescale of about 5 minutes, and was detectable for about 30 minutes. At the beginning of the sequence, the CH4 emission extends over about 10 arcsec along the slit. The slope of the emission shows drastic variations over the emission regions, corresponding to a large range of rotational temperatures. Assuming, as a first step, that methane lines are unsaturated, the rotational temperature, in the first image, is estimated to about 700K at the center (emission peak). On the edge (leading side), a different spectrum is observed, with a much weaker intensity, which may indicate different temperature profiles in the center and on the edge. A modeling of these emissions is in progress, which will give important constraints on the temperature profiles at the impact site and around. 02.05 Friedson A. J.* Goguen J. D. Orton G. S. Hoffmann W. F. Dayal A. Deutsch L. K. Wells W. K. Hora J. L. Spitale J. N. Fazio G. G. Thermal Infrared Observations of the Impact of Fragment R at the IRTF The impact of fragment R was observed at thermal infrared wave-lengths of 7.8, 10.3 and 12.2 micrometers from the NASA/Infrared Telescope Facility on July 21 (UT), using the MIRAC2 mid-infrared array camera (Hoffmann et al., Infrared Phys. Technol. 35, 175, 1993). Thermal emission at the three wavelengths was sampled sequentially using a 2% circular variable filter, with an average time interval of 17 seconds between observations at different wavelengths. Continuous imaging of Jupiter in this mode began at 5:08 UT and extended to 5:55 UT. Clear evidence for enhanced emission from the impact region first appears at 5:41 UT, with the peak in fireball emission at all three wavelengths occurring 3.5 minutes later. The excess flux at each wavelength then falls to less than 20% of the peak value over a period of about 4-5 minutes. Results based on preliminary calibrations of the 7.8 and 10.3 micrometer excess flux indicate a source color temperature of 3650 +ll00/-600 K and, on the assumption that the source was optically thick, a solid angle of 1.5 +/- 0.5x1O^-l4 sr (equivalent to that subtended by a sphere about 110 km in diameter) at the time of peak emission. Fifty seconds later, the color temperature has fallen to 2050 +l50/-200 K and the solid angle is 3.2 +/- 0.6x1O^-l4 sr (equivalent spherical diameter about 160 km). Work in progress includes i) refining the absolute calibrations, particularly for the 12.2 micrometer data; ii) including the calibrated 12.2 micrometer data in the analysis to determine whether the excess fluxes follow a black body spectrum; and iii) least-squares fitting a physical model of the fireball to the data as a function of time. 02.06 Livengood T. A.* Bjoraker G. L. Kostiuk T. Romani P. N. Kaufl H. L. Wiedemann G. Ivchenko N. Mosser B. Sauvage M. Thermal-Infrared Imaging of the SL9 Impact Sites Using TIMMI at the European Southern Observatory We present initial results from a successful program of thermal-IR imaging that was conducted as part of the European Southern Observatory SL9 observing campaign using the Thermal-Infrared Multimode Instrument (TIMMI) on the 3.6m telescope, during and following the collision of comet Shoemaker-Levy 9 with Jupiter. We obtained complete or nearly- complete 10 micron light curves during the A and H fragment impacts (3.26-second sampling), and extensive multiwavelength imaging of impact sites after the initial explosive phenomena, with filters at 5, 7.8,10.1,10.65,12.1, and 13.3 microns. Observations extended up to seven nights following the last impacts, with spatial sampling of 0.63 or 0.47 arcsec per pixel on a 64 x 64 pixel detector array. Many impact sites were still discernible as of our last observations, possibly due to either the persistence of non-equilibrium species (e.g., NH3), heating by aerosols in the stratosphere, or simply long radiative time constants for gaseous emission. The impact sites are sufficiently large that their spatial extent is resolved in these images. These observations were conducted jointly with a program of B. Mosser (related abstract, this meeting). TAL acknowledges support as an NRC Research Associate at NASA/GSFC during this work. 02.07 Halthore R.* Bjoraker G. Livengood T. Allen J. Jr. Kostiuk T. Stolovy S. Herter T. Kaufl U. Energy Deposited in the Jovian Stratosphere by the Impacts of Comet Shoemaker-Levy 9 Light curves in the 7.7 micrometer band observed using the Kuiper Echelle Grating Spectrometer (KEGS), for the G and K impact sites of comet Shoemaker-Levy9 on Jupiter show a rapid cooling of the hot core in the stratosphere. As the impact sites become visible over the limb, temperatures of the hot cores derived from the water emission lines are seen to be in the 500 K range (Bjoraker et al., this meeting). The horizontal size of the hot core can be estimated using the methane emission at 7.7 micrometers provided methane abundance is not altered in the hot spot. From the light curves in the methane emission, the temporal evolution of the size and temperature of the hot core are obtained. Results will be compared with those of TIMMI camera (ESO), an imaging instrument that observed the impacts in the 10 micrometer band. TIMMI will allow us to study the long term evolution of the impact sites. 02.08 Bjoraker G. L.* Herter T. Gull G. Stolovy S. Pirger B. Detection of Water in the Fireball of Fragments G and K of Comet Shoemaker-Levy 9 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 20 spatial and 128 spectral elements at a resolving power of 9000. The principal objectives were to search for H20 emission lines near 22 and 24 micrometers and to measure the stratospheric temperature using CH4 emission lines at 7.7 micrometers. It was necessary to switch between these 3 wavelengths during each flight. At the peak of the fireball for the G and K fragments, the intensity of the CH4 emission lines increased by a factor of 30 from pre-crash levels. Within the 7.67-7 72 micron bandpass, we detected 3 emission lines of H20. The lower state energy levels of these transitions are populated only at high temperatures (about 5OO K). The intensity of the water lines dropped by an order of magnitude in 15 minutes. Spectra at 22 and 24 micrometers were obtained after the peak of each fireball. No dramatic change in either the continuum level or depths of telluric H20 lines were observed. The long wavelength channels are sensitive to the temperature of the upper troposphere and to large amounts of modestly heated water. We conclude that the water came from the impactor, not from Jupiter, based on a combination of KAO and ground-based data. A quantitative estimate of the water abundance will be required before determining whether the impactor was a comet or an asteroid. 02.09 Sprague A. L.* Hunten D. M. Witteborn F. C. Kozlowski R. W. H. Wooden D. H. Bjoraker G. KAO Observations of Jupiter During and Following the Impact of Comet SL-9 Fragments R and W Using HIFOGS (4.9-9.4 and 9.3-14.5 Micrometers) Observations of Jupiter during and following the impacts of two segments of Comet Shoemaker-Levy-9 were made July 21 and July 22 1994 from the Kuiper Airborne Observatory using the High Efficiency Infrared Faint Object Grating Spectrograph (HIFOGS) [1]. An emission peak at 6.6 micrometers identified as H20 is prominent following the R impact and is seen in spectra following W. Line ratios indicate that the water temperature is near 500K. The Q branch of the 7.8 micrometer band of CH4 rapidly rose to 11 times brighter (5^h 45^m) than pre-impact measurements. It decayed by 25% in the next 3 minutes (by 5^h 48^m) following the R impact. A large increase was also seen at these wavelengths following W but the factor is not yet known. Also seen is a large emission increase of acetylene at 13.7 micrometers following both impacts and other, unidentified emissions. The KAO new out of Melbourne, Australia. HIFOGS has cryogenically cooled aperture and filter wheels, grating, and a linear array of 120 Bi-doped Si detectors. To increase the spectral range slightly, and to increase the resolution (decrease the wavelength sampling increment), standard stars and Jupiter were measured at four grating settings spanning wavelengths of 4.9 to 9.4 micrometers and 9.3 to 14.5 micrometers. Residual telluric absorptions are removed by calibrating to spectra of alpha CMa and alpha Cen when possible or by using atmospheric transmissions generated by the HITRAN data base and the NASA Ames ATRAN program. Spectral shape is removed by correcting ratios using alpha CMa which has been well-characterized using the KAO in previous flights. 1. Witteborn F.C. et al. Astro. Soc. Pacific Conf. Series Astro. IR Spec. Conf. 365-372 (1993). 2. Cohen et al. Astro. J. 104, 5, 2030-2044 (1992). 3. Cohen et al. Astro. J. 104, 5, 2045-2052 (1992). 02.10-P Harrington J. Dowling T. E. Hammel H. B. Mills J. R. Hoffmann W. F. Dayal A. Wells K. Sprague A. Hora J. L. Deutsch L. K. Fazio G. G. Baines K. H. Friedson A. J. Orton G. S. Yanamandra-Ficher P. A. IRTF and HST Observations of the Dynamic Response of Jupiter's Atmosphere to the Impact of Comet Shoemaker-Levy 9 We present images of Jupiter to be obtained immediately before and for several weeks after fragments of comet Shoemaker-Levy 9 impact the planet. We report dynamical effects of the impacts on the atmosphere. If sufficient energy is deposited in the atmosphere, the predicted behavior, including inertia-gravity wave excitation and vortex generation, acts as an atmospheric probe that constrains structure and dynamics. Imaging of reflected sunlight with the Hubble Space Telescope (HST) Wide-Field and Planetary Camera 2 (2159, 2553, 3344, 4090, 5407, 8922, 9534 Angstrom) and NASA Infrared Telescope Facility (IRTF) NSFCAM facility camera (1-3 micrometers) probes the upper ammonia cloud level (approximately 150 mbar). Imaging of thermal emission with NSFCAM (4-5 micrometers) and the Arizona/SAO/NRL Mid-Infrared Array Camera (5-20 micrometers) on the IRTF probes the stratosphere and troposphere (approximately 30-500 mbar) with a vertical resolution of 1-2 scale heights. 02.11-P Zahnle K. Mac Low M.-M. More Consequences of the Collision of a Comet and Jupiter The pieces of the former Comet Shoemaker-Levy 9 struck Jupiter during the week of July 16-22 1994. We divide the general impact phenomena into four phases. (1) Atmospheric entry should have been accompanied by an entry flash, probably only detectable by the Galileo spacecraft. (2) Aerodynamic forces cause the impactor to explode. We show that the apparent altitude of the explosions is consistent with the analytical model proposed by Zahnle and Chyba et al, with numerical models calculated by Mac Low and Zahnle and Yabe et al., and with dynamically- based estimates of fragment masses suggested by Scotti and Melosh and Asphaug and Benz. (3) The explosion produces a fireball that propagates most quickly up the wake, as predicted by Takata et al. and Crawford et al. The fireball's luminosity fades over a timescale of 30-60 seconds. (4) Each explosion produced a plume that reached thousands of kilometers above the cloudtops. The plumes appear to have been dusty and so illuminated when they reached sunlight. The plumes rose and fell over a period of ten or twenty minutes, governed by the simple laws of ballistics. When plume material (dust) fell back on the atmosphere it was reheated and glowed brightly in the thermal infrared for a period of order ten to twenty minutes; a large fraction of the impact energy was spent thus. Geometry introduces additional factors that complicate interpretation of the observed light curves. 02.12-P De Jong E. M. Ingersoll A. P. Toigo A. Video Representation of Shoemaker-Levy 9 Impact We present a video animation of the five phases: entry, plume, pressure wave, internal gravity wave, and long-lived vortex following the impact of comet Shoemaker-Levy 9 into Jupiter. The entry phase lasts a few seconds and ends when the bolide has lost its initial kinetic energy. The plume (fireball) phase lasts a few minutes and ends when the ejecta have fallen back and the strong shock waves have dissipated. The pressure wave phase lasts for 1-2 hours and ends when the waves' amplitude drops to unobservable levels. The gravity wave phase lasts for 1-2 days and ends when the wavefronts have been broken up by the zonal winds and the waves' amplitudes have fallen to unobservable levels. The vortex phase may last indefinitely if the vortex can adjust to a stable configuration in the zonal shear flow. We have borrowed heavily from numerous authors and, where necessary, have parameterized their results. The objective in producing the video is educational -- to provide physical insight into the various phenomena and their interrelations in space and time. References: T. Ahrens et al. GRL 21,1087 (1994), J. Harrington et al. Nature 368, 525 (1994), D. Hunten et al. GRL 21, 1091 (1994), A. Ingersoll et al. GRL 21, 1083, (1994), M. Marley Ap. J. Lett. 427, L63 (1994), K. Zahnle and M.-M. Mac Low Icarus 108, 1 (1994) 02.13-P Marley M. S. Dayal A. Deutsch L. K. Fazio G. G. Hoffmann W. F. Hora J. L. Hunten D. M. Sprague A. L. Sykes M. V. Walter C. Wells K. W. A Search for Seismic Waves Launched by the Impact of Comet Shoemaker-Levy/9 The impact and explosion of each fragment of comet Shoemaker-Levy/9 (1993e) into Jupiter's atmosphere was predicted to launch an acoustic "seismic" wave that would probe the interior structure of the planet. We attempted to detect the thermal infrared signature of this wave as it returned to the visible atmosphere after refraction in the interior of Jupiter. To do so the mid-infrared array camera MIRAC2 was deployed on the IRTF to search for perturbations in the 7.8 micrometer CH4 stratospheric emission feature following several impacts. The planned S/N ratio of 100 per pixel in an exposure of 140 sec would have allowed detection of the approximately 0.1K temperature fluctuations expected after impacts exceeding approximately 10^28 erg. Owing to uncooperative weather, the seismic wave search was conducted only in the aftermath of the moderate-sized R impact and technical problems limited the exposure time. Our dataset thus consists of 240 7.85 micrometer images of Jupiter obtained in the 90 minutes after the impact. The seismic wave was expected to appear as a growing ring centered on the impact site during this time period. No such structure is obvious in our current, slightly-processed images. With substantial further reduction and analysis we expect to either detect the wave feature or place an upper limit on its stratospheric temperature amplitude and, ultimately, the impact energy. 02.14-P Lognonne Ph. Billebaud F. Vauglin I. Merlin Ph. Sybille F. Mosser B. Lagage P. O. Gautier D. Drossart P. Seismic Waves Generated by the SL-9 Impact The 10 micron camera from the Observatoire de Lyon was mounted on CFHT between July 21 and July 27 1994. Due to hurricane Emilia, no observations were done July 21, e.g. for the last impacts V and W and only post-impact data were obtained between July 23 and July 27. 5 hours of continuous observations were recorded in the 10.57-12.94 micron filter between July 24 and 27, at a rate of one image every 30 seconds, for a search of trapped pressure waves with period greater than 5.5 minutes, and several images were taken with 4.5-5, 9.16-10.08 microns and CVF filters for a search of slow thermal changes, related either to gravity waves or non-reversible heating of the Jovian atmosphere due to surface waves. The post impact seismic program on CFHT was coordinated with two other telescopes, all using the same type of instrument: TIMMI camera at the 3.6-m telescope at ESO (Chili), and CAMIRAS, from CEA, at the NOT (Canary Islands). The analysis of these data is under progress. Synthetic simulations on the excitation of normal modes and surface wave have shown that the post-impact seismic waves are observable for impacts with energy greater than 10^{21} J. However, the seismic waves are strongly focused at the antipode and a seismic signature at the antipode remains possible for lower impact energies [Lognonne et al., 1994]. If positive, seismic observation will allow the inversion of a profile of seismic velocity. From the amplitude of seismic signals, it will also be possible to give a range for the explosion released by the impact. 02.15-P Collins M. D. McDonald B. E. Kuperman W. A. Siegmann W. L. Jovian Acoustics and Comet Shoemaker-Levy 9 A three-dimensional acoustic model that handles spatially varying acoustic parameters and wind fields has been developed and applied to model global-scale sound propagation from the impact sites of the fragments of Comet Shoemaker-Levy 9. To achieve these modeling capabilities, it was necessary to neglect nonlinear effects. Although nonlinear effects are important near the impact sites, the spatial distribution of compressional wave energy predicted by the linear model should be qualitatively representative. The vertical dependence of the acoustic parameters and the latitudinal dependence of the wind are known from Voyager data. The Jovian atmosphere contains a sound channel, which is a layer of relatively low sound speed that ducts acoustic energy by refraction and contains the cloud layers. Since several of the fragments exploded just above or within the cloud layers, a great deal of acoustic energy was released in the sound channel. The zonal winds consist of cells that blow in opposite directions and act as acoustic waveguides. The acoustic model predicts that energy in the sound channel is pinched into well-defined beams by the zonal winds. The two strongest beams form in wind cells to the east and west of the impact sites and remain well defined at great distances from the impact sites. Since these beams are caused by geometric effects and delimited by acoustic shadow regions, they should be the most prominent acoustic features away from the impact sites. Images from the Hubble Space Telescope show evidence of cylindrical acoustic wave fronts propagating in the sound channel near the impact sites. Processed data might reveal structured wave fronts away from the impact sites. This work was supported by ONR. 02.16-P Maillard J. P. Drossart P. Bezard B. de Bergh C. Lellouch E. Martin A. Caldwell J. Owen T. Atreya S. Waite H. Yelle R. FTS Spectroscopy of the SL9 Impact Sites on Jupiter The collision of comet Shoemaker-Levy 1993e with Jupiter has been observed with the Fourier Transform Spectrometer at the CFHT. A 2.5- arcsec aperture (corresponding to 8000 km on Jupiter) has been selected, and the impact sites were observed by offset guiding on a galilean satellite. The goal of the observations was a search for modifications of the jovian composition after the impacts, at tropospheric and stratospheric levels. As a priority, the 4.7-micron window was observed to search for modifications of CO, with a resolution up to 0.1 cm^-l. In the same spectral range signatures from PH3 and CH3D are also present. Impact sites B, C, F, G and L were observed in this spectral range, showing increased cloud opacity but no dramatic changes in the spectral absorptions. Two fragments (C and R) were monitored at the time of the impact, directly observable from Hawaii, in a 3.3-micron filter covering the 2850-3020 cm^-l range, with a resolution up to 0.19 cm^-l. This region is dominated by the R-branch of the nu(sub)3 band of methane which blocks all the solar reflected light in normal jovian spectra. For both impacts an emission peak appeared at 3000 cm^-1 with further structures between 2860 and 2950 cm^-1, lasting less than 20 min. Preliminary simulations with a 500-K temperature profile down to the 10- micronbar level and normal below, indicate that these structures could possibly be due to methane emission. Additional observations were made in the 2.2-micron window on fresh impact sites (G and H) allowing the detection of a haze continuum and of the pressure-induced spectrum of H2. 02.17-P Korsun P. P. Sizonenko Yu. V. High-resolution Spectra of the Satellite Reflections During the Comet Shoemaker-Levy 9 Impacts on Jupiter Long-slit CCD spectra of Jupiter were obtained with the 2.6-m telescope of Crimean Astrophysical Observatory, ZTSh, on 19-22 July, 1994. One set of the observations was carried out at Nasmith focus and the wavelength region covered 4600-10,250 angstroms at a resolution of 4.5 angstroms. The other one was carried out at coude focus and the spectra extended over various parts of the same spectral region at a resolution ranging from 0.2 to 0.8 angstroms. The spectrometer slit was aligned along the parallel of the impact to provide a spatial analysis in this direction. Combined investigations of Nasmith spectra, both the spatial profiles for different spectral regions and extracted spectra for different sites of the crash latitude, show that the impact spots have some spectral peculiarities. The main results of our investigations we can summarize as All impact sites have low albedo with respect to undisturbed surface of Jupiter in at least 4600-8000 angstroms wavelength region. No obvious changes in the spots spectra shape are apparent, except for 4600-5700 angstroms region where albedo of the spots slightly increase to the blue. Observed spots showed considerably less methane absorption in the 8900- angstrom band. Such effect was somewhat lower in the 1-micrometer CH(sub)4 band from the H and D+G+S+R sites spectra and no detected in the other observed methane bands. We are grateful to R. E. Hershberg, Yu. F. Mal'kov, and V. I. Pronik (CrAO) for their support and assistance in our observations. 02.18-P Wannier P. G. Spilker T. R. Submillimeter Observations of the SL-9 Impact from KAO We will use a heterodyne submillimeter radio receiver on NASA's Kuiper Airborne Observatory to measure the abundance and vertical distribution of water in the Jovian stratosphere immediately following the collision of comet Shoemaker-Levy. Our specific target is the 548 GHz line of ^18O water, minimizing interference by terrestrial water. The Jovian stratosphere is normally dry but water vapor, once introduced, will persist for relatively long periods, possibly years. Water may be injected by the fireball following a deep penetration, or by sublimation of cometary ice. After injection, lateral stratospheric circulation should distribute the water over the planetary disk within a few days. The heterodyne technique yields very high resolution (upsilon/delta upsilon approximately equal to 10^6) spectra that can be used to infer both depths of the observed water, from pressure broadening, and longitudinal distributions, from timing and Doppler shifts. 02.19-P Orton G. Baines K. Friedson J. Goguen J. Yanamandra-Fisher P. A'Hearn M. Esterle P. Lisse C. Weaver H. Wellnitz D. Hoffmann W. Hunten D. Dayal A. Sprague A. Sykes M. Wells K. Marley M. Fazio G. Deutsch L. Hora J. Jewitt D. Joseph R. Deming D. Kostiuk T. Bjoraker G. Fast K. Livengood T. Zipoy D. Griffith C. Dowling T. The NASA/IRTF SL9 Observing Campaign The NASA Infrared Telescope Facility campaign (July 12 - August 7, 1994, supplemented by later observations) used near- and middle-infrared cameras NSFCAM and MIRAC2, near- and middle-infrared spectrometers CSHELL and IRSHELL, and the Goddard heterodyne spectrometer in several investigations. (1) Fragment K was observed an hour before its impact. (2) The impact fireballs were investigated from fragments C (2.248 microns), G (2.295 and 4.780 microns) and R (7.85, 10.30 and 12.20 microns). (3) Particulates high in the stratosphere at impact lasted for many weeks. (4) Temperatures were perturbed between 10 and 400 mbar pressure. (5) The temperature field was searched for seismic waves, and both the temperature and cloud field were searched for inertia-gravity waves. (6) The north polar H(sub)3^+ aurora brightened after the impacts; the stratospheric hot spot was suppressed during the impacts. (7) NH3 was transported into the stratosphere, C2H4 and C2H6 abundances was enhanced, and tropospheric PH3 was depleted. (8) Little influence of the increased dust environment on Jupiter's ring was detected in the near infrared. 02.20-P Smythe W. D. Carlson R. W. Weissman P. R. Hui J. Segura M. E. Baines K. H. Matson D. L. Johnson T. V. Leader F. E. Taylor F. W. Encrenaz T. Drossart P. Galileo Infrared Observations of the Shoemaker/Levy-9 Impacts of Jupiter A direct view of the impact sites of the comet fragments from the Galileo spacecraft allows a study of the fireball expected to occur during the first minutes following each impact. Predicted temperatures of a few thousand degrees place the spectral emission within the wavelength range (0.7 to 5.2 microns) of the Near Infrared Mapping Spectrometer, which will observe several of the events in seventeen wavelength bands. The spectral bands chosen exhibit differing gas opacities and allow sounding at various depths in the atmosphere. These spectral positions include the Jovian spectral windows (e.g. 2.7 and 5 micron windows and shorter wavelength continuum regions) and a band for H(sub)3^+ emission. To ensure observation of the impacts, given spacecraft pointing errors, the scan platform will dither across Jupiter with a 5 second period. Data will be recorded for 64 minutes for 4 impacts, although only a portion of these data will be selected for playback. Initial pecks at the data for the G and R impacts show that the scan platform and the NIMS instrument operated correctly. Normal Jupiter spectra were obtained. Approximately the first 3 minutes of the G impact spectra are expected to be available in time for the DPS meeting. Preliminary results of the spectral properties and time development of an observed fireball will be presented. 02.21-P Kim S. Dumas C. Orton G. Brooke T. Spencer J. Spectroscopic Study of the SL9 Impact Areas of Jupiter with the CTIO IRS We obtained spectra of Jupiter's atmosphere in the 3 - 5 micron region with the newly modified Infrared Spectrometer (IRS) on the 1.5-m telescope at the Cerro Tololo Inter-American Observatory (CTIO) between July 16 and 25, 1994 (UT), during and after the impacts of fragments of comet Shoemaker-Levy 9. Analyzing the spectra of the impact sites, we have found the following: (1) The upsilon(sub)3 band of CH4 has been shown in emission on the major impact areas; (2) The spectral characteristics of the impact clouds are very similar to that of the usual polar haze. The polar haze is dark in UV and visible ranges, and bright in methane bands in the visible range. The polar haze is bright between 1.5 and 4 microns, wherever CH4 absorption is strong. The reason why the impact areas are bright in the CH4 bands is that the impact cloud altitude is high (approximately 1 mbar as we reported previously. See DePoy et al., this conference), so that there is less CH4 absorption above the impact clouds than above the normal cloud layers; (3) We found brighter global H(sub)3^+ emissions than the normal condition. In contrast, we found no significant increase in the H(sub)3^+ emissions at the major impact sites, and frequently we did not detect H(sub)3^+ emissions finding only CH4 upsilon(sub)3 band emissions at the major impact sites. We are now investigating the following possible phenomena: ( 1 ) CH4 upsilon(sub)3 band emissions at other latitudes, (2) altered vertical and hortzontal distributions of atmospheric molecules, haze particles, and cloud levels; (3) the presence of new molecules and comparisons with model calculations; and (4) vertical mixing ratios and temperatures of tropospheric molecules to determine whether fragment penetration is deep enough to cause tropospheric mixing. As a part of a network of internationally coordinated observations, including other near-infrared spectroscopic obsetvations in the U.S. southwest, Hawaii and Australia we are comparing our observations with other observers' results to shape a unified scenario of the impacts. 02.22-P Dinelli B. Miller S. Achilleos N. Lam H. Tennyson J. Jagod M.-F. Oka T. Geballe T. Brooke T. Ballester G. Trafton L. Infrared Spectroscopic Studies of the Impacts of Fragments B and C of Comet Shoemaker Levy-9 The effects of the Fragment B and C impacts of SL9 on Jupiter were monitored at wavelengths around 3.5 microns, sensitive to ionospheric H(sub)3^+ emission, using the CGS4 long-slit spectrometer on UKIRT. Data obtained prior to the impacts, with the slit aligned east-east along the S45 region, showed that emission from the western region of the planet was somewhat stronger than that from the east. But this pattern was reversed with the approach and impact of Fragment B, even though this fragment made hardly any impact deeper into Jupiter's atmosphere. The Fragment C impact gave rise to emission due to high-J lines of methane (principally P(18) and P(l9) of upsilon(sub)3), at intensities which were at least two orders of magnitude greater than the ambient ionospheric H(sub)3^+ emission. The most intense H(sub)3^+ line (upsilon(sub)2 R(3,3)) in our spectra also appeared to brighten by this amount. But, since the CH4/contiupsiloupsilonm emission swamped the weaker lines we were monitoring, we cannot be sure that all this intensity is due to H(sub)3^+. Initial fitting of CH4 lines to our spectra suggests that temperatures in the plume some 15 miupsilontes after nominal impact were around 1300K, falling to about half this during the next 40 miupsilontes. But CH4 fits the spectra we obtained poorly, indicating that other -- thus far unidentified -- species may be important. 02.23-P Crawford D. A. Boslough M. B. Robinson A. C. Trucano T. G. Numerical Simulations of Fireball Growth and Material Motion During Comet Shoemaker-Levy 9 Impact on Jupiter The CTH shock-physlcs code ls used to study two- and three-dimenslonal representations of the impacts of Comet Shoemaker-Levy 9 on Jupiter. The simulations are divided into two closely linked parts. The first part consists of two- and three-dimensional simulations of entry, deformation and breakup of the cometary fragments. Realistic material models incorporating melting, vaporization, dissociation and ionization of the comet fragments and Jovian atmosphere are used. The comet fragments are modeled as 1-, 2- and 3-km spheres of fully dense (0.95 g/cc) and porous (0.3 g/cc) water ice, porous silicate (1.0 g/cc) and distended clouds of unbound water and silicate fragments (average density 0.01-0.2 g/cc). Depth of penetration and energy deposition per unit altitude are tabulated for comparison with other models. The second part of the simulation takes, as its input, material location, velocity, pressure,,temperature and density from re-entry, deformation and breakup studies. These are mapped into a three- dimensional computational mesh for rendition of fireball growth and evolution. Lagrangian tracer particles track the motion of cometary debris and Jovian atmospheric constituents. At 120 seconds after the impact of a fully dense 3-km cometary ice fragment (M = 1.4 x 10^16 g), the total mass of the resulting fireball above the 1-bar level is 6.8 X 10^l6 g (4.9M) with 0.2% (1.5 x 10^14 g, 0.01M) of the fireball as impactor material. At this time, 4.4 x 10^l6 g (3.1M) of atmosphere has been uplifted above the l-bar level from below the tops of the Jovian water clouds. Assuming a 10^-3 relative abundance of water in the water clouds, our simulation shows that approximately 4 x 10^13 g of water (0.003M) has been entrained in the lower portion of the fireball. Dependence of material motion over the range of fragment models described above will be discussed. This work is supported by the National Science Foundation under Agreement No. 9322118 and performed at Sandia National Laboratories supported by the U.S. Department of Energy under contract DE-AC04- 94AL85000. 02.24-P Biraud Y. G. Cuisenier M. Marten A. Rosenqvist J. Moreau D. Muller C. Balega I. Chuntonov G. Maslov I. Near Infrared Photometric Observations of the Comet SL9-Jupiter Collision at the Zelenchuk Observatory Near infrared observations of the comet impacts with Jupiter have been performed at the SAO 6-m telescope (Zelenchuk/Caucasus) using a Fourier spectrometer. Because of an unpredictable technical problem, the observations were limited to spectro-photometry between 3.3 and 4.2 microns with a resolving power around 300. Observations were performed on July 17, 19, 22, and 27, consisting of a total integration time of 3 hours. The K and W impacts were mainly monitored. Preliminary results did not show any obvious variability of the 3-4 microns low resolution Jovian spectra but a more detailed investigation of these data will be reported in order to determine possible _small_ variations of the Jupiter'continuum. In addition to infrared spectra, CCD cameras provided visible information on the location, shape, and size of the impacts. After filtering and digitization, a spatial resolution of 0.4 arcsecond could be attained. 02.25-T Trafton L. M. Atreya S. K. Noll K. S. McGrath M. A. Weaver H. F. Caldwell J. J. Yelle R. V. Comet SL9-Jupiter Impact Events: HST Search for Enhanced Stratospheric CO and H2S During the SL9-Jupiter impact events, HST will obtain exploratory spectra of the impact sites. One objective is to detect and measure cometary and photochemically enhanced CO and H(sub)2S in Jupiter's stratosphere. This will be attempted using the GHRS to obtain spectra of the 4th Positive bands of CO in emission and the FOS to get spectra of the H2S absorption bands from 2000 - 2700 Angstrom. The potential enhancement of CO from these sources is significant and diagnostic of the cometary CO + H20 content, and of the photochemistry between the Jovian hydrocarbons and uplifted Jovian H20. The H2S is diagnostic of the cometary sulfur abundance, and possibly of the reservoir of Jovian sulfur. SESSION 03 ....... Comet Shoemaker-Levy 9 III Monday, 1:30 - 3:30 Crystal Ballroom A Cindy C. Cunningham and Glenn Orton, Moderators 03.01 Mac Low M.-M.* Zahnle K. Comparison Between Observations and Numerical Models of the Impact of Comet Shoemaker-Levy 9 on Jupiter We present our latest numerical models of the impact of comet Shoemaker-Levy 9 on Jupiter and compare to the observations. We use the astrophysical gas dynamics code ZEUS to model the initial entry, explosion, and plume development for a period of 10 minutes after impact of each fragment. We show that if the incoming fragments had diameters of order 0.5 km as suggested by Asphaug & Benz, we can give a consistent model of the observations. Our entry models show that these small fragments explode in the ammonia cloud layer, explaining the observations of ammonia but no water. Published models predicting deeper penetration were flawed by inadequate resolution. The light curves from the resulting 10^27 erg explosions are as dim as observed by Galileo. Finally, our plume models show that these explosions are still large enough to spread cometary material over distances of 10,000 km in the upper stratosphere, as observed. This work was supported by the NSF through grant AST 93-22509, and by NASA through grant NAGW-2379. Computations were perfomed at the Pittsburgh Supercomputing Center. 03.02 Gurwell M. A.* Muhleman D. O. Philips J. A. Grossman A. W. Millimeter Imaging of the Comet P/Shoemaker-Levy 9 Impacts on Jupiter Observations were made during each transit of Jupiter during the impact events of comet SL9 using the OVRO millimeter interferometer (located near Big Pine, CA). The data were taken in the 3.0 mm continuum (July 16, 17, 22, 23) and the 3.38 mm continuum (July 18-21). The latter observations include spectral correlator data centered on the HCN(1-0) transition. These OVRO observations are part of a larger effort to measure the microwave response of Jupiter to the impacts, and include observations taken at the BIMA millimeter interferometer and the Very Large Array. The main source of opacity at millimeter wavelengths is gaseous ammonia, with the weighting function peaking near 0.8 bars. Pre-impact modeling had suggested that the fragments of SL9 would penetrate to well below this level. This penetration would perturb the vertical ammonia distribution at and near the impact site, affecting the millimeter brightness temperature in spatially localized regions on Jupiter. We are currently in the midst of the arduous reduction of this large dataset, but at this point we see no obvious effects of the cometary impacts in maps of the continuum brightness temperature. Our current maps are of poor SNR, due to rapid phase