Workshop Information for IAU Colloquium 156 Here is information on the various workshops that will be held each afternoon. If you wish to participate in any of these workshops, please contact the relevant convenor(s) expressing your interest. -------------------------------------------------------------- TUESDAY 9 MAY 1995 2:00 PM - 6:00 PM Title: Flash Reflections (limits, etc.) Convenor: Mike A'Hearn (email@example.com) Charter: There is still dispute about whether Galileo's SSI and PPR observed the impacting bolide, the rising fireball, or some combination of the two (NIMS clearly observed a rising fireball). Earth-based optical observations of flashes in reflection from the satellites are very puzzling. The most realistic looking flashes imply luminous energies considerably in excess of those observed by Galileo (albeit at different wavelengths) and none of these most realistic looking ones have been confirmed from multiple sites. Other flashes, looking more like noise, have been confirmed at multiple sites to within about one or two seconds. Some flashes appear to occur at times that slightly precede the precursor events observed in the near infrared. This workshop will attempt to extract all possible observations from different sites and correlate their times both with the times of optical flashes observed at other sites and with observations in the infrared. *************************************************************************** Open letter from Mike A'Hearn to Workshop Participants Dear Colleagues, Like many other workshop organizers for IAU Colloquium 156, I am making a plea for data relevant to the workshop I am organizing. I will be running the workshop on impact flashes seen either at the limb or in reflection from the satellites. I presume that the emphasis will be on the optical flashes but the timing of optical flashes relative to the precursor flashes seen in the near infrared is also very important so I hope that we will have participation by the infrared observers also. I would particularly welcome participation also by experienced meteor astronomers who could comment on the colors of the flash expected from a bolide in Jupiter's atmosphere. I would like to start the workshop with a preliminary table of all the possible detections of flashes. Many people have already published in one way or another the times of possible flashes but others have not. The key things I hope to accomplish at the workshop include establishing the accuracy of the times, identifying all possible coincidences from more than one site, and directly comparing actual photometric records for shape and size of the flash. We will then try to assess which of the detections might be real. After considering the photometric records of flashes, we will consider the spectroscopic detections. The instrumental problems are entirely different and the interpretation may also be different. I would appreciate hearing from anyone who might have data relevant to the impact flashes, particularly from people whose observations have not already been announced. A list of times of possible event sin your data is the most urgent item. Meanwhile, to aid in searches of other datasets, I will provide in a week or two a complete list of the times available to me at that time. This list will be posted on the SL9 electronic bulletin board. Mike A'Hearn University of Maryland firstname.lastname@example.org PS: Note that this message is not being sent from my normal email address so please do not use the reply command as it will only delay my receipt of your message. ***************************************************************************** Title: Synthesize Phenomena (G & W) Convenor: Alan Fitzsimmons (email@example.com) Charter: The primary aim of this workshop will be to examine the available observations (and interpretations where held!) of the impacts of the G&W fragments. During the workshop we should address two primary goals: (a) The creation of a complete as possible chronology for both impacts, from first detection to subsequent evolution of the plume debris on Jupiter. Given this, it is important that the most crucial datasets (high-resolution imaging, multi-wavelength spectroscopy) be discussed. In particular, are there observables associated with these impacts that may not have been seen with other events? (b) To inter-compare data from both ground and space-based observatories. For example, How does the visual luminosity as seen by Galileo compare with the IR precursors observed from the ground? Can we produce a multi-wavelength spectrum for the plumes at any given instant? How does the grain size in the plume compare with the corresponding particulates in the impact site hours/days/weeks afterwards? Title: Synthesis of Impact Times Convenor: Don Yeomans (firstname.lastname@example.org) Charter: The goal of this workshop will be to examine the impact time predictions in light of the relevant observations from ground-based observatories, the Hubble Space Telescope, and the Galileo spacecraft and to determine, to the extent possible, the actual impact times and their associated uncertainties. --------------------------------------------------------------- WEDNESDAY 10 MAY 1995 2:00 PM - 6:00 PM Title: Synthesize Phenomena (K, L & R) Convenor: Richard West (email@example.com) Charter: 1) Establish for each impact an overview of what material was really obtained (instrument characteristics, observation epoch, "quality"), so that all groups know which material may complement theirs 2) Divide this material in to a logical (chronological) sequence of the main "phases", e.g. Flashes - Plumes - Splashes - Early direct views - Long-term evolution. 3) Within each of these phases, animate a "joint discussion", i.e. by combining all what is available from the individual impacts (in my case, K, L and R) to find out whether there are: a) full agreement among the groups about what was observed b) obvious disagreements, which should then be exposed and possibly elucidated, whereby a list of "open questions" may be prepared c) any particular, "unique" observed events, which indicate qualitative differences between the individual impact sequences 4) To invite the model builders to comment on the various points that come up during each of the "phases", immediately following the discussion among the observers. In particular: a) does the information from the observations as presented make it possible to draw some (new) conclusions about the process(es)? b) can we now put some numbers on the models, or, which of these observations may be particularly crucial for the models? For instance, which "combinations" of observations are especially useful and should be pursued? 5) At the end, to "synthesize" the outcome of these discussions on the spot, i.e. to mention the main points which came up and suggest specific lines of action. ***If you want to participate in this particular workshop, ***it would be helpful if you would fill out the following ***questionaire and return it to Richard West. ------------------------------------------------------------------------------ QUESTIONAIRE (please fill in and return to firstname.lastname@example.org before May 5)) FOR ALL OBSERVERS OF THE K, L AND/OR R EVENTS Thank you for taking a few minutes to fill this in ! Name : Observatory : Which event (K, L or R) : Type of obs.(direct/spectr): Telescope : Instrument : Wavelength interval : Approx. ang. resolution(") : Approx. spectr. resolution : Observing interval (UT) : No. of frames/spectra : Observing conditions : Provisional results (brief): e.g. timings, emitters Related papers published : ------------------------------------------------------------------------------ Title: Comparison of Impact Models Convenor: Glenn Orton (email@example.com) Charter: This workshop will overview various approaches to the impact modeling in light of available observational results. In general, what are the points on which the models are in significant agreement? For example, is there a consensus on the interpretation of the most sensitive 3-peaked impact lightcurves? Among the disagreements between models, which originate with the numerical approach and which with basic assumptions about the important processes? What hope is there for reconciling or discriminating among the approaches based on the observations? Are there physical observations which are not well described by the models? What has been most significantly changed about our concepts of the important processes in impacts by the observations of this event? Title: What about the Weak/Missing Impacts? Convenor: Hal Weaver (firstname.lastname@example.org) Charter: During our studies of SL9-Jupiter impact phenomena, we have focussed our attention primarily on the most spectacular events. However, perhaps much can be learned by assessing what happened during the smaller impacts. Since the magnitude of the impact phenomena varied from being visually spectacular to undetectable, nature has provided a range of input parameters over which model predictions can be tested. Some of the questions addressed in this workshop include: 1) How do we rank the impacts? 2) What was the most sensitive technique for detecting post-impact phenomena? 3) Do observations of the fragments prior to impact provide clues as to what impact phenomena were produced? 4) Can variations in impact phenomena be explained solely by fragment size variations, or are structural variations in the fragments also required? 5) Exactly what happened to the SL9 fragments that "disappeared"? In order to address these issues we need to synthesize data from both the pre-impact observations of the comet and the post-impact observations of Jupiter. --------------------------------------------------------------- THURSDAY 11 MAY 1995 2:00 PM - 6:00 PM Title: Magnetospheric Effects Convenor: Renee Prange (email@example.com) Charter: Signatures of the interaction of comet SL9 with the Jovian magnetosphere have been recorded in a variety of wavelengths from X rays to radioemission. They have been obtained at different times, including after the impact period. This worshop will first allow to organize the set of specific observations available (i.e. nature, date, coordinates, characteristics) in order to identify related events and any relationship with the comet fragment histories. Theoretical models have been developed, both before the collision, and after the effects were observed. Their ability to interpret the various sets of related events as a whole will be dicussed, as well as the need for any further theoretical effort. Anticipated topics might be grouped into - global activity - localized interaction of the coma with the high latitude magnetosphere - torus effects - electrodynamic effects on the impact field lines (including synchrotron radiation) Title: Pre-1992 History of SL9 Convenor: Paul Chodas (firstname.lastname@example.org) Charter: Following the motion of comet Shoemaker-Levy 9 backwards in time can provide clues to the nature and origin of the object. An accurate pre- breakup ephemeris is essential in searching for possible detections of the parent object in existing images of the Jupiter region. If we could be sure of the ephemeris, even a non-detection would be useful in putting limits on the progenitor nucleus size. Backwards integrations can also shed light on the capture mechanism and provide insight into where the object came from. Questions addressed in this workshop include: * How do the results of various backward integrations compare? * What are the uncertainties in pre-breakup ephemerides? * What searches have been conducted for pre-breakup detections? * When was SL9 captured by Jupiter and from what kind of helio- centric orbit? * Is it important to model the perturbations due to Jupiter's oblateness and the Galilean satellites? * Are we omitting any important perturbations? * How do we solve the Humpty-Dumpty problem, ie, how do we determine the orbit of the progenitor nucleus from the orbits of the fragments? Title: Multiwavelength Atomic and Molecular Abundance Determinations: Reconciling Differences Convenor: Keith Noll (email@example.com) Charter: Determination of the chemical composition of Jupiter's atmosphere in regions perturbed by the impact of SL9 is a key observable that can be used to constrain models of impact-induced chemistry and possibly the composition/size/depth of the impactors. Several of the most abundant molecules were observed in more than one transition at wavelengths from the UV to the mm. In some cases, the abundances derived from such observations differ by orders of magnitude. The purpose of this workshop will be to explore the details of independent abundance determinations for gases such as CO, NH3, and C2H2 in an attempt to characterize possible causes for divergent results. Possible avenues to explore are rapid variation of molecular abundance with altitude, assumptions about model inputs such as temperature, differences in beam size and sample area, temporal variability, and issues of data quality. --------------------------------------------------------------- FRIDAY 12 MAY 1995 2:00 PM - 4:00 PM Title: Conference Summary Convenor: Gene Shoemaker Charter: This is a plenary session in which Gene Shoemaker will attempt to summarize the highlights from the meeting.