Q kein Hit? / News from Space / Langlebige Spuren: Rep.#12 21.7. 2:30 CST ------------------------------------------------------------------------- Anstelle des Standardanfangs ueber die endlosen Wolken, die die Anden be- decken, beginnen wir lieber weit jenseits davon: Etliche Satelliten und Raumsonden haben Daten der Einschlaege geschickt, als da waeren: IUE PRESS RELEASE 19 JULY 1994. The spectacular images from many ground based and space observatories have more than fulfilled the expectations of astronomers all over the involving essentially all observatories in the world, to study the first predicted astronomical catastrophe: the collision of the pieces of Comet Shoemaker-Levy 9 into the atmosphere of planet Jupiter will continue for a few days to come. While still awaiting for the forthcoming impacts of the remaining 12 pieces of SL9 into the atmosphere of Jupiter, many scientists are also working around the clock to interpret the results of other types of observations, as important from a scientific perspective -if not more- than the images, even though less spectacular. [...] European space scientists are collaborating with their American colleagues in an extensive observing program with the International Ultraviolet Explorer Space Observatory (IUE). The unique nature of IUE, which is a truly international collaborative Project (ESA/NASA/PPARC), has made it possible to take the first spectra only 20 minutes after the first plumes of impact A had risen beyond the limb of Jupiter, and before they were dispersed by the strong stratospheric winds of Jupiter. These spectra are of particular interest, because they are taken at ultraviolet wavelengths, a range which allows to study the upper layers of the Jupiter atmosphere (hundreds of km above the visible clouds) and can only be obtained from space since the ultraviolet range is inaccessible to ground based observatories. The spectra taken just after the impact of comet fragment A have shown a clear increase in the reflectivity of the Jupiter atmosphere by some 20% compared to normal. Only two hours after the first spectrum (and less than 2.5 hours after the impact) the UV brightness of the plume had already decreased considerably, and the ultraviolet reflectivity was very close to its normal value. Comparison with spectra taken under similar conditions before the impact showed new absorption lines at wavelengths of 176 and 178 nm with a possible localized emission near 182 nm. The identification of these lines with specific atoms or molecules has not been possible yet because of the difficulty in the identification of molecular lines of carbohydrates, many of which show emission lines in this wavelength range. Dr. Claude Emerich (IAS, Orsay) who is currently making the IUE observations at the ESA IUE Observatory in Spain suggests that one possible identification of the 182 nm emission line could be the emission of atomic sulfur, suggesting that the plume consists of the explode material of the comet nucleus. Ferner wird berichtet, dass der IUE keine blitzartige Aufhellung des Mon- des Europa gesehen hat, und dass die FOC des HST drei Tage vor Beginn der eigentlichen Einschlaege, als bereits Kometenstaub in die Jupiteratmo- sphaere eingedrungen war, keine Aufhellung der Jupiter-Aurora wahrnahm. Im Gegenteil ist sie ungewoehnlich finster - ist der Komet schuld daran? Und es gibt erste Voyager Ultraviolet Spectrometer Observations Observations of Jupiter by the Voyager 2 Ultraviolet Spectrometer began on 8 July and have been continuous except for gaps in downlink telemetry coverage. The wavelength range is approximately 50 to 170 nm. At this time we have examined data taken during the impacts of Shoemaker-Levy 9 fragments A, B, C, D, F, G, and H. We have not yet identified a statistically- significant signature from any of these fragments. More detailed analysis will follow, and Voyager observations will continue until 17 August. Bill Sandel LPL, U Arizona Ferner Direct impact observations: Galileo PPR results for Event L The Photopolarimeter Radiometer on the Galileo spacecraft observed Jupiter for 18 minutes during a period corresponding to earthbased observation times of UTC 200/22:09 to 200/22:27 for event L. The PPR has a single field of view that is about 4 times the size of Jupiter. A filter at 945 nm was used for these observations; the sample time was 0.4 sec. The L impact was seen at UTC 22:16:48. The brightness corresponds to about 4% the brightness of Jupiter itself. The signal rises to peak value in about 2 sec and then decreases over 35 sec to background levels. The shape of the light curve is very similar to that seen earlier for event H. Galileo is positioned to see the impact sites directly, at a distance of 240 million km; the phase angle of Jupiter is 51 degrees. Terry Z. Martin, Leslie K. Tamppari, and I. Claypool JPL L. Travis, A. Lacis, and J. Hansen GISS, New York Kein Glueck hatten dagegen die Space-Shuttle-Astronauten beim Jupitergucken: Televised interview with Columbia astronauts last night revealed their failure to observe any SL9 effects on Jupiter using binoculars. You'd think NASA would have splurged for a few bucks, considering the timing of this flight, and purchased some off the shelf equipment to rig up an STS observatory. Say a Meade or Celestron altazimuth mounted 8" SCT with a CCD tracker in the finder scope, and a Telrad. Bolt it to a bulkhead in front of a window in the cockpit and have at it! I bet the guys at JPL could have bought everything they needed during one afternoon's shopping around LA. But no! Had it occurred to them, NASA's administrators would have formed a committee, developed new standards, advertised for contract bids, changed the specifications several times, and maybe by the time of the next moon landing have a working prototype ready for ground tests. And who knows, perhaps they'd detect the spherical aberration pre-launch! [Dies aus sci.astro] Actually it wouldn't have done any good -- no matter how big a telescope you could have put within the shuttle's crew cabin. Remember that the STS-65 IML-2 mission is a microgravity laboratory mission. Anything else, whether it's the Apollo 11 anniversary, P S/L-9 event, Japanese woman, etc. etc. is secondary and cannot interfere with the microgravity experiments. The shuttle's attitude for this mission is tail to Earth, nose pointed away from the center of the Earth, with the right wing pointed in the direction of travel. I don't know if you've ever been in any of the shuttle simulators or mockups, but the eleven windows in the crew cabin are TINY! I sat in the Shuttle Training Aircraft and was impressed with how small the view was. And then the instructor had me put in some cardboard cutouts and explained that THAT was the actual field of view out of the front windows. Let's say you put in a telescope which fills the entire crew cabin into the shuttle (never mind room for the astronauts or removing the interdeck floor). And double the size of the windows. You still wouldn't be able to see anything much better than what you could already view from within the crew cabin with the fancy binoculars which are flown on EVERY shuttle mission. (and these are not cheap binoculars). Remember that the shuttle crew is no closer to Jupiter than we are. And they are moving rather rapidly, and the impacts are still on the other side of the limb. When you add the small size of the shuttle's windows and the shuttle's gravity Gradient attitude -- the view from the shuttle isn't any better than a site with good seeing at a high altitude (e.g. Manua Kea) with good weather. A better question is a year ago, when it was determined that it was certain that there was a collision -- why didn't NASA decide to swap the STS-65 IML-2 payload with the STS-67 ASTRO-2 telescopes (much larger telescopes within the shuttle's cargo bay). A year in advance it would have affected both mission's timetables, but would have been feasible. In addition it would give ASTRO-2 a much better time of the year to fly. Granted ASTRO-2's intruments are designed for galactic use - not planetetary views. For example the Ultraviolet Imaging Telescope has such a large field of view that Jupiter shows up as a small disk with a couple of stripes plus four distinct dots (the Galilean satellites). One ASTRO-2 astrophysicist told me that if they were in orbit they woul certainly look at Jupiter, but wouldn't expect it to be much better than other observatories. I asked Dr. Lucy McFadden about the feasibility of asking NASA to swap IML-2 for ASTRO-2 some time ago and apparently the idea had not occured to anybody! and a somewhat cynical comment about JPL going out to purchase a home telescope. If it was possible I'm certain they could do it in time, but with JPL's reputation for going over budget -- I'm certain it would cost four times what it would cost a typical consumer to purchase the same telescope. Philip Chien [ebenfalls sci.astro] Und wo wir schon bei der NASA sind: hier der aktuelle Pressekonferenz-Report From: huette@andrior.harvard.edu (Susanne Huttemeister) * Spektroskopie mit dem HST Es ging v.a. um ein Spektrum des "Bull's Eye" der G-Impakt-Site, dessen Wellenlaengenskala auf dem Fernsehschirm nicht zu lesen war. Ich glaube visuell/UV. Es war ein Verhaeltnisspektrum vorher/nachher, und am deutlichsten zu sehen war ein breites "Absorptionsfeature", das ganz klar NH3 sei. Dann war da ein bemekenswert deutlicher "Ripple", der, so der Spektroskopiker, voellig ueberraschend kam, und erst unidentifiziert blieb. Nach Abstand und Breite der gesehenen Linien musste es ein schweres, aber einfaches Molekuel sein. Derr Mann machte es echt spannend und beschrieb lang und breit, wie sie sich stundenlang von einem Molekuel zum naechsten vorgearbeitet haetten, bis sie endlich morgens um drei die Identifikation gehabt haetten: Eindeutig Schwefel, S2. Es gaebe auch noch ein schwaches Feature, dass konsistent mit H2S sei, aber da seien sie sich weniger sicher. Das S2-Feature aber sei "totally unexpected" gewesen. Es sei zwar schon mal (in IRAS-Araki-Alcock) kometares S2 gesehen worden, aber auf der anderen Seite seien S2 und NH3 Molek"ule, die er eher mit Jupiters Atmosphaere als mit einem Kometen in Verbindung bringen wuerde, weswegen er tentativ die Interpretation bevorzoege, dass das dunkle Material seinen Ursprung in Jupiter habe. * Magnetosphaere Nun wurde es etwas chaotisch und undeutlich, zumal die Franz"osin zu schlechter Tonqualitaet auch noch einen Akzent hatte. Ausserdem war mindesten zwei Zwischenfragen zu entnehmen, dass Lucy McFadden auch nicht ganz mitbekam, was sie interpretierte. Aber die Bottomline ist recht erstaunlich und (glaube ich) gibt korrekt wieder, was die Frau sagte: Alles basiert auf UV Aufnahmen, sowohl mit der WFPC als auch Mit der FOC (die sei europaeisch, vermerkte die Franzoesin ganz stolz). Es waren keine der erhofften "precursors", also Vor-Impakt-Veraenderungen zu sehen. Jupiter sieht im UV normalerweise recht eintoenig aus, nur die Polkappen-(Aurorae) sind hell. Die noerdliche war deutlich schwaecher als die suedliche. *Nach* den Impakten (die sich im UV als sehr auffaellige schwarze "Loecher" zeigen) tauchten 2 neue helle Polkappen-Features auf - aber IM NORDEN!! Allerdings sehr viel weiter suedlich als der Auroraguertel normalerweise reicht, eine Schaetzung war, in breiten von ca. 60 Grad. Die Franzoesin interpretiert das als Impaktbezogen: Koma(?)bestandteile der Fragmente seien im Jupiter Magnetfeld gefangen, beschleunigt und entlang der Feldlinien nach Norden transportiert worden. * Amateuraspekte (David Levy) David meinte, seiner Meinung wuerde die Schwaerze und Groesse der visuell sichbaren Impakt-Sites ganz weit oben in der Hitliste von "Was ist die groesste Ueberraschung" stehen. Er spekulierte entlang der Internet - Diskussion "Was waere, wenn der Komet nie gefunden worden waere" und es ist auch ganz interessant, sich mal zu ueberlegen, was wohl passiert waere, wenn Amateure ganz unerwartet grosse schwarze Flecken in der Naehe von Jupiters Suedpol haetten auftauchen sehen. Waere man auf einen Impakt gekommen? Waere man darauf gekommen, dass es viele Fragmente waren, die da nacheinander einschlugen? David betonte, dass jeder versuchen sollte, eines Teleskops habhaft zu werden: "This is the time to get out with a small telescope and look at Jupiter - the best time since Galileo!" Ein anderer Report dieser GSFC press conference, Noon EDT, July 20, 1994: Names approximate. Sentences fragmentary. Typed in real time. No spell-check or proof-reading. Roger Yale? U. Az. Hubble FOS, UV G-spot absorption feature spectrum. 270 nm, 5% rippling pattern in spectrum: Sulfur gas, S2. This was not expected. H2S, hydrogen sulfide may also have been seen. S2 has been seen in Iras-Iraki-Alcock. sulfur compounds also seen in other comets and in Jupiter. French woman involved in Hubble (I didnUt catch name): WFPC near-UV images shows strong auroral ovals at both poles. Aurora seen by faint object camera as early as July 13, perhaps because of leading dust. North aurora consistently fainter. IUE also sees this.July 18 WFPC shows two auroral SPOTS near North pole, perhaps because of material splattered off southern impacts or comet itself, getting ionized, and following the magnetic field lines. David Levy Dark spots being easily visible by amateurs is a surprise. G-spot is still most prominent, but there are enough spots that some are always visible at any Jovian orientation. One theory: comet dust is making them dark. Lucy McFadden Images from ground-based observatories: Lick Obs. Speckle image of Jupiter. Beautiful detail, shows dark spot and ring around it. Series of IR images (1-4 microns) shows many prominent bright spots. Most prominent at 4 microns (bright spots against dark Jupiter). Kuiper observatory: Gordon Bjoraker, looking for water and temperature for G and K fragments. Fireball 25 times brighter than Jupiter. Temperature from 10 micron measurements of methane in Jovian stratosphere. IRTF Mauna Kea: Ammonia and methane images. Galileo photopolarimeter/radiometer saw H impact. McDonald Observatory; L site under very good observing conditions, IR and optical observations. Can see spot structure with eyepiece. H-spot can be seen detatched from limb. Query: You already knew about sulfur, why the surprise? Internet report of comet material seen. Response: H2S is what we have seen in Jupiter. Rest of Q&A missed. David M. Palmer palmer@alumni.caltech.edu [aus sci.astro] Und gleich noch einer [ebenfalls sci.astro] , weil's so spannend war...: Okay, now that I've seen part of the conference on tape (the part where they showed the aurora images) the auroral spots in the southern hemisphere are polarward of the impact sites, but not all the way to the auroral oval. Then there are spots in the northern hemisphere that correspond to the conjungate locations of the field lines. I didn't hear them say anything about being surprised that they were "at the same latitude as the impacts". They are definitely *not* at the same latitude, they are poleward by about 5 to 10 degrees. The puzzling thing to me is why the northern spots are so much brighter than the southern ones. Marc Hairston--Center for Space Sciences--University of Texas at Dallas Mehr Instant Science, dies nun aus dem SL9-Mail-Exploder: NASA/IRTF reports confirmation of stratospheric ammonia from emission lines near 908 and 948 cm-1 (11.0 and 10.5 microns) in a highly localized area over the impact site of fragment K near on 1994 July 20 near 8 UT. The observations were made by the University of Texas IRSHELL spectrometer at a resolving power of 12000. A search for H2S lines near 1149 and 1234 cm-1 showed no obvious emission. C. Griffith, D. Kelly, J. Lacy, G. Orton and B. Bezard for the IRTF SL9 Science Team. Update on JCMT detection of HCN at positions of several fragments: We have now detected HCN 4-3 at the positions of fragments C, F, G, H. We have searched for it, but not detected it from B and L. The site of fragment G impact produced the strongest line yet observed: peak antenna temperature 1.2 K, near Gaussian profile with width =3D 5.3 km/s, integrated intensity 6.2 K km/s. We are monitoring the impact sites of F, G and H to examine the change in the lines over time. The strong line at G measured 21 hours after impact seems to have disappeared 35 hrs after impact. Emission is also no longer observed from C. But F and/or H are still showing emission (they are 6" apart and so not unambiguously resolved by our 14" beam). We have also carried out long (0.5 hour in bad weather) integrations on the sites of fragments F and C at CO 3-2 (345 GHz), but did not detect anything. Combining the integrations on both sites gives an rms noise level of 150 mK (at 0.7 km/s resolution). We also integrated down to a 1-sigma noise of 420 mK (0.5 km/s resolution) on the site of fragment H without seeing anything. Matt Griffin, Andre Marten, Henry Matthews, Gary Davis, David Naylor, Greg Tompkins, Byron Han. The Caltech Submillimeter Observatory has tentatively detected the 216.7 GHz (2 2 0 - 2 1 1) line of H2S at Jupiter following the fragment B impact. In our first observations of the impact site, ~1.5 hours after the predicted impact time, we apparently observed an extremely narrow (less than 1 MHz) absorption feature at the 4 sigma level. Individual scans showed that the feature, initially ~1.2 K in depth, decreased steadily to ~0.8 K over the next ten minutes. We then observed the northern hemisphere at the same frequency and did not detect the line. When we returned to the impact site 18 minutes after the last southern hemisphere integration, the feature had faded into the noise. Observations following the fragment C impact did not detect H2S. This may be related to the markedly different characters of the fragments B and C impacts. T. Phillips, E. Serabyn, T. Spilker, and E. Weisstein Zurueck in die Gegenwart: Weitere Eilmeldungen ueber die laufenden Einschlaege: The impact of fragment N was detected at 2.34 microns as a faint flash beginning at UT 10:35:23 and lasting until UT 10:38:31. Subsequent narrow band imaging failed to detect the impact site. Peter McGregor and Mark Allen Mount Stromlo and Siding Spring Observatories We report observation of Q1 fragment impact on Jupiter at 10 microns with the Saclay CAMIRAS camera mounted on the Nordic Optical Telescope. UT was 20 21. Less bright than L impact seen yesterday. French Spanish Swedish observing team at La Palma The Q impact site is now in view. V band imaging with the swedish solar telescope on La Palma shows it to be very similar to the nearby L site: a central dark spot and a diffuse concentric ring. The relative position between the sites now makes Jupiter look like the man in the moon. The La Palma seeing is not very good, but it is just about possible to see an elongation of the central dark spot, presumably due to the double impact of the Q fragments. Mats Lindgren Uppsala Astronomical Observatory SPIREX observed the fragment Q1 and Q2 impact sites appearing over the limb of Juptier. Conditions around the impact were not good, with clouds coming in and out. The Q2 impact was not easily seen, due to confusion with the older impact sites. Q1 was observed at 20:20 UT, and was bright, as expected. Mark Hereld, Hien Nguyen, Bernard J. Rauscher, Scott A. Severson Astronomy & Astrophysics Center, University of Chicago Ueberwaeltigend, wie alle glaubten (auch die gleich drei Radiosender, die heute ueberraschend fuer Live-Interviews anriefen - und gestern gab es in der ARD of all places eine einstuendige Sondersendung[!] zu den Kometenimpakten!) war der Q-Doppeltreffer also offenbar nicht. Und nun weitere Amateur-Beobachtungen: Another excellent evening's observing at Cambridge with 30-cm refractor (date 1838, by the way). Main points were as follows. -- Sites K, L, G paraded across the disk; they are all more spectacular than ever, very large and dark, about as big as the GRS, each with a black spot like a satellite shadow in the north-following corner. [...] -- Limb-brightening north of site K as it approached the p. limb. The STZ along here was bright anyway, but seemed particularly bright at the limb from 20.26 to 20.58 UT (when seeimng worsened). This was the clearest example of a phenomenon I have often suspected over the last 4 days: diffuse light areas adjacent to the dark sites when near the limb, but not so evident when further onto the disk. Has anyone recorded this on images? -- Possible weakness of the Q impacts. No flashes observed visually (of course), but later there was no dark spot in the expected place for Q2, and only a rather faint, southerly dark area for Q1. Seeing was getting bad at that time but it seemed inferior to site H observed at the same phase two days ago. [...] (If Q2 failed, it fits neatly into the pattern that all nuclei which were displaced tailward in the comet have either broken up, disappeared, or impacted without an explosion. Were these nuclei made of some tenuous tacky polymer, subject to solar wind/radiation pressure??) John Rogers (BAA) im Mail-Exploder. Und in sci.astro etwas aus Aachen! I've watched Jupiter from 20h UT to 22h UT July 19th. At about 21h30, a huge dark feature appeared on the SW limb of Jupiter. It looked like (as somebody else has described it) the beginning of the umbral phase of a lunar eclipse. Seeing degraded rapidly as Jupiter sank low to the horizon, and it even became difficult to see the aequatorial bands, but the dark area remained visible.=20 I also saw one clear and one supposed other dark spot when starting to observe at 20h UT. These were smaller, perhaps the size of a satellite shadow. They were at the SE edge of Jupiter and the bigger one disap- peared behind at the limb at about 21h30, when the larger spot appeared. Observing was done with an 8 inch f/5 Newtonian at 200x. Seeing was miserable, most of the time. Dieter Kreuer rwth-aachen.de Northern Districts Society for Amateur Astronomers Inc. Various back-yard sites Sydney NEW SOUTH WALES AUSTRALIA 22:15 pm EST (12.15 UT) 20th July 1994 Fragment K's aftermath was on the limb at or about 20.20 EST (10.20 UT) when three independent observers (mostly at powers about 200x, scopes from 6 inches to 10 inches) saw a meteor-like pin-shaped flash above the site of the K-fragment blemish. These observations were assisted by the contrast at the darkened portion of the limb. By about 20.45 EST (10.45 UT) the impact site of fragment N was clearly visible and by 21.45 pm EST (11.45 UT) the site could be seen to be as large as the K-fragment blemish, with a very similar structure - a central hole and a scimitar-like smudge beneath it (to the south). The latitude is slightly higher than the K-fragment site. When both sites were close to the central meridian, the appearance was very like a pair of caricatured and heavily browed eyes - 'the eyes of Jupiter' if the effect persists. From Powell, Wyoming, near Yellowstone Park, I watched Jupiter from 9 P.M. to 11:30 P.M. Sporadic clouds made viewing difficult for most of the first hour, but eventually they cleared off and all I had to deal with was turbulence, which wasn't too bad for most of the time. This would be approximately 0300-0530 UT, night of July 19 (morning of July 20 UT). At 9:50 I spotted a relatively large dark spot in the far southern hemisphere, about midway between the following limb and the central meridian. I tried every trick I know to make it go away, just in case it was an optical illusion. It stayed, even through a change of eyepiece. The instrument was a C8 with a 10mm Plossl, =3D200x. I attempted to time its transit across the CM, but more clouds came along and made viewing intermittent so I was unable to obtain a precise time. My best estimate is 10:10 (0410 UT) plus or minus 5 minutes. [...] Overall evaluation: IT'S BEAUTIFUL!!!!!!!!!!!!!!!!!!!!!!!!! Seeing such a dark anomaly on the Pastel Planet is truly a once-in-several-lifetimes opportunity. Dave Ha ha! Well guess what? I (and several others from my AS) have clearly observed big fat black spots through a Meade 60mm, with 1" eyepieces!!! I shit you not. In my opinion the contrast may even be slightly better than some of the 8" Newtonians I have observed the same spots through (although the resolution is not even close). Glenn mailbox.uq.oz.au Two dark spots were *very* clearly visible last night (ca. 0100 UTC July 20th) in a 4" Genesis refractor at 70x. They were also detectable (though not easily) in a Celestron S-80 spotting scope at 65x (straight viewing with no diagonal). The s-80 is a 80mm f5 achromat (*not* ideal for planetary work) and probably vignettes the objective, so it's effectively a bit smaller. Didn't try the 50mm f12 Meade I have, but it might be interesting! Bob Atkins AT&T Bell Labs Murray Hill, NJ Nice view of three impact sites last night. At 3 hours UT (July 20), two were easily visible. The leading site was the larger and darker than the following one, almost the size of the NEB. They reminded me of sunspots, with a dark, almost black core surrounded by a dark gray annulus. The following spot transited at 4:08 UT, which works out to 37.8 degrees in the S II longitude system (thanks to Dan Bruton for the longitude info). From impact longitudes supplied by Sky & Telescope, this is probably the H impact site. While the H site was in transit, the leading site was almost on the limb. A rough estimate of it's longitude identifies it with the G impact site. Another impact site, about the size of the H was rotating into view. This was most likely the A site, if I've calculated my longitudes correctly. These observations were made with a 28 cm SCT. Clear skies, Bill Yesterday evening July 20th at 20:20 EDT (0:20 UT) I set to watch for any SL9 impact markings on Jupiter. I was in for an astonishing surprise. I thought that if I was lucky I could see impact site G but what I got instead was a phenomenal view of impact sites K close to the preceding limb, L close to the meridian and G coming out of the following limb. These are big! (or should I say "jupiteresque"?). I will most certainly try to follow the activity on Jupiter as closely as I can for the once in many lifetimes event. Gilles Gagnon dgbt.doc.ca | The Communications Research Centre Zum Trost fuer die, die (wie wir hier...) immer noch leer ausgegangen sind: Hearing the call to all amateur astronomers, I dusted off my 3.1" Meade refractor last night and set it up on the beach in Long Beach, CA to join in on the SL9 fun. I pointed it at Jupiter and immediately came to the conclusion that size matters. Yes, I could discern the disk and a few belts but that's it. No gigantic Earth-size holes, no blinding comet explosions, no screaming Jovians running for cover. Nothing. Just Jupiter, calm and bland as usual. --John So - wie lange duerfen wir noch hoffen, etwas zu sehen (momentan sehen wir hier nicht mal mehr von einer Kuppel zur naechsten - NEBEL!)? Ich fragte den Exploder: Subject: Longterm 'decay' rates of impact site phenomena requested As we here on Cerro Tololo are already completely clouded out for days and probably more to come, we are increasingly wondering: How long might the impact sites remain visible after the actual sequence of impacts is over? Two CCD teams here have their telescopes till the end of the month. Could those who have been blessed with regular views of the impact sites please give us rough estimates about how quickly the impact sites so far have faded, e.g. A and C, and if there seems to be a general 'time constant'? Thanks, Daniel Fischer on behalf of the Cerro Tololo observers Und Antwort kam (E-)postwendend von einem der fuehrenden SL9-Theoretiker! From: Clark Chapman account psi Subject: Time constant I hope you all have better weather. The spots are changing a bit visually, but they tend to be lasting a long time. E looked the same last night as it had 2 nights before. Count on there being spots in the visible well through the end of the month. Also, for those with telescope time through the end of the month, remember that the extension of the comet train starts impacting on the EARTH-FACING side of Jupiter starting about July 26th or 27th. [Siehe auch den Auszug aus einem IAU-Zirkular ganz am Ende!] Clark Chapman Zu der Einschaetzung der Langlebigkeit der dunklen Flecken passen auch diese wenige Stunden alten Beobachtungen vom Pic du Midi-Observatorium: We have tracked from 400nm to 2.3 microns the spotr. Visual aspect: H (strong), E (+F?), A (expanding), C, K (large elongated nucleus surronded southwards by a halo) L (dark oval nucleus with a shadow in its South East flank), G (dark nucleus and shadow as L) and Q1 (+N?). As seen from the size and morphology of the spots, impacts L and G were the most energetics, a fact confirmed by our detection of the impact flash L described yesterday. The albedo of all spots were: in the continuum from 400 nm to 1 micron: very low low albedo under the 619 asnd 725 nm methane bands. Higher reflectivity in the 890 nm CH4 band and in teh 2.16 micron K band. Here are revised impact parameters predictions for the remaining 10 fragments: The solutions have not changed for fragments N, T, U, and V, as we have no new data for these. The solutions for fragments P2, Q1, Q2, R, S, and W have been updated using Dave Jewitt's astrometric positions of July 19.3, the only new data we have received since the impacts began. It is clear from the observed impact phenomena that our predicted impact times have been early by an average of 5-10 minutes. We attribute this to systematic errors in the Guide Star Catalog, which was used to reduce most of our astrometric positions. Consistent with this is the fact that the latest data, which are reduced relative to more accurate catalogs, invariably tend to move the predicted impact times later in our solutions. As a result, we feel the times below are still likely to be early, but we have refrained from applying an arbitrary correction or extrapolating the trend towards later impact times. We have, however, inflated the impact time uncertainties to account for the observed systematic errors. Except for Q2, these revised impact times are only a only few minutes later than those in our previous table, dated July 16. The impact time for Q2 took a large jump (15 minutes later), because we now compute its orbit directly from the data, instead of using a tidal disruption approach as before. The predicted impact time for Q2 is now only 17 minutes before Q1. Paul Chodas 1994 July 20 07:00 UT [...] Und dass es dann vielleicht noch nicht vorbei ist, behauptet ein IAUC: PERIODIC COMET SHOEMAKER-LEVY 9 (1993e) Z. Sekanina, P. W. Chodas and D. K. Yeomans, Jet Propulsion Laboratory, communicate: "Between July 22 and at least the last week of September Jupiter will be bombarded by the debris that populated the comet's west-southwestern trail. Between July 27 and Sept. 22 the impact sites will be located on the planet's near side as viewed from the earth. The collisions will occur at a decreasing pace both in terms of the event rate and the characteristic size of the individual particulates. We estimate that this debris consists of centimeter- to subkilometer-sized fragments, so that explosive phenomena triggered by the impact events will be much less powerful than those associated with impacts of the major fragments. Yet, searches for both possible individual events and any collective effects are encouraged. Our model predicts that the jovicentric latitude of the impacts will vary from -44 deg in late July to +42 deg in late September. The earth-Jupiter-impact site angle will reach its minimum of 69 deg on Sept. 3, at which time the impact geometry will be the most favorable for earth-based observers. All impacts will be near Jupiter's morning (eastern) limb. After Sept. 22 the impact sites move back to the far side, but by that time the impact rate will have diminished considerably and Jupiter will be approaching conjunction with the sun." 1994 July 19 (6029) Brian G. Marsden Und ganz zum Schluss noch ein kleines(?) Raetsel, live vom Berg nebenan... Date: Thu, 21 Jul 1994 2:15:07 -0400 (EDT) From: Tim Livengood Reviewing my e-mail and thinking about what I`ve seen, something important seems to have received little mention. When we first observed the F site from La Silla at 10 micron, it was EXTREMELY clearly visible and well-separated from the E site. It distinctly was NOT observed at 2 microns by the IRAC2B camera (Jockers et al.) on La Silla at the same time. The Palomar team a little later mistakenly (I think) identified it as mixed-up with E. After about 20 hours, I start finding reports of distinct spots associated with F. The original non-detections of F at wavelengths shorter than 10 micron are, I think, real. Thus, it took substantial time for the atmosphere to cool sufficiently for the F-region volatiles to condense. Late-night thoughts from a cloud-shrouded ESO, Tim Livengood Und es gruesst alle D. Fischer