Vorerst letzter Kometenbericht (Nr.15): Jupiters neues Gesicht. 25.7.1994 -------------------------------------------------------------------------- Die letzte Nacht hier auf dem Cerro Tololo in den chilenischen Anden hat noch einmal fuer die entgangenen Live-Impakt-Freuden entschaedigt (der ge- neite Leser wird sich erinnern, dass die beiden einzigen hier wolkenfrei beobachtbaren Impakte B und F ziemlich unergiebig waren): Extrem klar, Zodia- kallicht im Westen, Milchstrasse ohne Ende und angedeutete 'Green Flashs' nicht nur beim Sonnenuntergang sondern auch den Untergaengen von Venus und Jupiter (marginal --- waere das erste Mal ueberhaupt...). Lediglich das Seeing war nicht mehr so gut wie an den vorangegangenen Abenden, aber er- neut konnte Jupiter 5 Stunden lang gut verfolgt werden. Jeder Punkt der Wolkenoberflaeche und der schwarzen Ungetueme, die darueber schweben, konnte in den drei vergangenen Naechten mit 1-2 Bogensekunden Aufloesung in Augen- schein genommen werden - Zeit fuer einen ersten Bericht, der an den Mailex- ploder, die CTIO WWW SL9 Page und (via CfA) an sci.astro gegangen ist: The State of the Dark Spots on Jupiter in the Week after the Impacts Following extensive visual studies of all major dark spots on Jupiter with a 16-inch Cassegrain on Cerro Tololo Interamerican Observatory, here is a summary of what the inidividual regions looked like to the eye (no filters available) under ideal conditions on the nights 22/23 and 23/24 and under deteriorating seeing on the evening of July 24th. Emphasis is on the areas where something happened and not so much on the fate of each individual fragment; sometimes it's not clear anyway which part of a region relates to which impact. The listing is in alphabetical order = time sequence of the major impacts; at this time all the 'regions' addressed are clearly distinct. The "Visibility Index" is a spontaneously invented measure for how easy a region is to see (and thus of the minimum telescope size required): Index I is so striking that even a 60 mm spotting scope (of sufficient magnifica= tion) should not fail to show it, II is harder but should be easy in any decent amateur telescope, III may require a more advanced scope and/or good seeing as the lack of a dark Core gives these regions much lower contrast. A (after 7 days): A pretty faint elongated mass of dark material, oriented in a more or less North-South direction, connected (?) to the STrB. No dark nucleus visible. Visbility Index III C (after 6 days): A grey mass, extended both in NS and EW direction. No dark nucleus evident. (A distinct White Oval Spot is in the STrB north of it! The surrounding belt is significantly darker.) Visibility Index II-III E (after 6 days): Consists of a dark Core (Visibility Index I) and an extended winglike halo, with two spikes pointing towards the West, the more northern one is connected to the STrB. Whole Structure: Vis. Ind. I-II G (after 5+7 days): By far the most impressive feature, no aging whatsoever visible over three days! The dark Core is extremely long (and connected to the much smaller but very dark R site), to the south is an extended Halo, almost as dark. The structure looks like a squirrel :-) Its extent in longitude was measured to roughly 30 000 km. Visibility Index I H (after 4 days): Probably the most bizarre impact site. There is a dark Core, but from it emanate long wisps of dark material to both the SW and N. Visibility Index I. (After 6 days): Structure resembles a smoking volcano, sitting on the STrB, with 'smoke' extending to the WSW. Vis. Ind. I-II K (after 4+5 days): The secondmost impressive impact region after G, looks more like a sunspot group than any other. There's a very long (25-30 000 km) 'penumbra' in EW direction, inhabited by two big dark 'umbrae', while yet another 'umbra' accompanies these spots to the south. Vis. Ind. I L (after 3+4+5 days): Another quite bizarre region, with several dark Cores and halo structures, extending along a SE - NW axis. Visibility Ind. I Q (after 2 days): Mainly a dark Core (Vis. Ind. I-II) with a Halo (V.I. II-III). (After 4 days): Another, even smaller spot (Vis. Ind. II-III) precedes Q General Impression: All Regions of Visibilty Indices I and II are much darker than anything else on the planet except the occasional satellite shadow in transit; if you want to see the most awesome view I recommend times when G, L and K are all on the visible hemisphere [such as on July 23rd at 23:30 UTC]. No image in the visible that has been distributed on the network, by the way, has *really* captured the awesome size, darkness and wealth of detail of the major impact areas - not even the recent images from the Space Telescope (where the 'normal' cloud features appear too prominent in comparision with the direct view the eye has, thus dimimishing the startling difference in contrast between the spots and the normal meteorology of Jupiter). Only HST's monochromatic view in the UV of several sites comes closer to the actual view. The drawings obtained at the CTIO 16" will be presented at the 2nd Meeting of European Planetary and Cometary Observers (MEPCO'95) in Violau, Germany, March 24-27, 1995 where Gene Shoemaker will be the keynote speaker and the face of Jupiter after the demise of SL9 should be the major topic. A collection will also be submitted to the J.A.L.P.O. and is also due to appear in the next edition of the newsletter Skyweek, available from the undersigned. Daniel Fischer, leaving Cerro Tololo today and heading back to Germany -> Im Kottsiefen 10, 53639 Koenigswinter, FRG; p515dfi@fs1.mpifr-bonn.mpg.de Ein aehnlicher Bericht war kurz vorher von der Jupitersektion der BAA veroef- fentlicht worden, obiger wurde aber unabhaengig erstellt. Kaum Differenzen: From: "John Rogers (Physiol)" Subject: Visible impact sites; Current listing; Thanks to all (1) LATEST VISUAL OBSERVATIONS, July 22 and 23. (Longitudes are tabulated below.) July 22 (20h-22h): James Lancashire (JAL) and Paul Doherty (PD), both using 30-cm telescopes. Site C: Still present after 5 days without substantial fading. Site K/U/W: The overall appearance has not changed much since July 20 but it now contains 3 (JAL) or 4 (PD) dark nuclei. Site L: Still large and dark. July 23 (19.30-21.30): John Rogers, 30-cm refractor. The appearance is just amazing - the planet really has been thoroughly carpet-bombed. Site L: Still large and dark after 4 days, broken into several components. Site D/G/S: Large and complex, perhaps the most impressive yet seen. As it approached the p. limb, there was a bright spot on the limb Np. it. Site R: A tiny black spot south of the main line of dark spots, close to D/G/S with a tiny bright spot between. (R and Q1 were identified from the longitudes given by the Hubble team; see below). Site Q1: A single black spot like a satellite shadow. Cannot see site N. Site H: Remarkable changes now it is 5 days old. It is a very dark spot, obviously north of the main line, but may have a black Sf. tip which would be on the line. Also, there was a light area f. it when coming in from the f. limb, and a bright spot p. it when on the disk. In general, the large spots have remained prominent for up to 5 days, but are distorting, as if stratospheric currents are carrying the 'smoke' to E. or N. or S. There are several indications that light material may be spreading through the region. We have to beware of visual contrast effects but what I see are: (i) local limb-brightenings as previously noted; (ii) distinct bright spots mentioned above; (iii) the STB seemed unusually faint all along these longitudes. Given the small size of sites R and Q1 (and the difficulty of disentangling S and W from previous sites), it appears possible that the comet had 3 classes of sub-nuclei: (i) those displaced tailward, whose impacts were not detectable (or barely so); (ii) the early 'on-line' nuclei, which produced prolonged fireballs and large scars, in proportion to their brightness in the comet; (iii) these later on-line nuclei, which produced briefer fireballs and smaller scars. **************************************************** (2) PRESENT LIST OF VISIBLE SCARS ---------------------------------------------------- Site \3 \3 \2 Date (HST) (vis) (vis) ---- ----- ----------- ------------ ------- A 185 178 107 July 19** (faint) C 224 219 148 July 19** K/W - 263-278-283 191-206-211 July 22** (JAL)=20 L - (mid.342) (mid.270) July 22 (lo-res; JAL) 330-348-352 260-277-281 July 20** D/G/S 25 (G) (6)-28-31 (293)-315-318 July 23** R 42 40.5 328 July 23 Q1 64 67 355 July 23 H 101 97 25 July 23 F? - - E 154 155 83 July 19** ---------------------------------------------------- The second column gives the System III longitudes reported by the Hubble team (as of July 23, presumably from early images). The third and fourth columns give our most recent longitudes, in Systems III and II, from visual obs'ns on the dates given (p.m.). These are by myself except for those marked JAL. Where one value is given, the scar looked like a satellite shadow (except for A); where three are given, they are the p. end, the black core, and the f. end. Values in brackets are approximate. We have not looked at sites E, A, C since July 19; possible update tonight but the weather is about to break... **These were reported by Maria Womack et al. at the Lowell Obs. to be still bright in 890-nm images on July 21 (a.m.). As before, our longitudes tend to be slightly lower than Hubble's even for the 'black spots', presumably because they measure the very darkest point which is near the f. edge. ---------------------------------------------- In general, the scars get bigger and/or darker after the first passage, and so far only site A has faded (after 3 days). Sites C and H have been observed for the longest without further disturbance, and are still prominent after 5 days. However, the shapes change over several days. ---------------------------------------------- I do not know of any visual sightings of scars for the 'dud' impacts, viz.: B; F (though it is consistently reported in the infrared); P2; Q2; U (went into K/W); T (went into E/F); V (went into E/F); nor for the small impact, N (close to Q1). The Hubble team today report that the Q2 and N sites "are so small that they are difficult to detect in our images". The exploder has carried single reports of sites T (Wm.Herschel Tel.), P2 and U (Table Mtn.Obs.), detected on the disk in infrared, but were they distinct from the complex structure developing in previous sites? **************************************************** (3) THANKYOU BUT NOT GOODBYE As the dust begins to settle, I really want to say thankyou to everyone who has been involved in disseminating the information about this event. Thanks particularly to Paul Chodas and Don Yeomans for producing all those predictions; to Anne Raugh and Lucy McFadden for operating this exploder service; to Glenn Orton for the International Jupiter Watch (Atmospheres) bulletins prior to the impacts; to anyone else involved whose role I have overlooked; and to EVERYONE who has sent messages about your observations and ideas. Your messages are being summarised as quickly as possible for circulars to amateur astronomers, who will certainly carry on observing. This has been the most exciting (and sleep-deprived) week that I can remember. It has really been impressive how much everyone has achieved. The press and public must be impressed too: that astronomers can get spectacular predictions right (for once!); that observatories and spacecraft have performed so well (especially Hubble S.T.); and that astronomers worked together so well, and got such splendid data and images out so quickly. The public image of science must have got a real boost from this. Regarding the visual spectacle, I concur with Clark Chapman that the big impact scars are the most prominent transient spots ever seen on Jupiter, and are easy for anyone with an 8-cm telescope or bigger. ('Transient' excludes the GRS which, we must admit, was stunning around 1880 if not 1990.) Certainly, as Tom Hockey's list shows, such a thing has never happened before in recorded history. (I can say so having reviewed all historical observations as part of the work for my comprehensive book, 'The Giant Planet Jupiter', which is being published by CUP in spring, 1995 - excuse me for slipping that in...) The show is not over; amateurs will track these scars as long as possible (and keep an eye open for meteors on the limb). I'll be happy to send periodic reports through the exploder - and to receive updates from everyone else - for as long as Anne and Lucy think it's worth operating. Best wishes: John Rogers (British Astronomical Association). Zum Thema SL9 und die Oeffentlichkeit passt dieser bemerkenswerte Artikel aus New York City - Starparty im Central Park... From: John Pazmino Newsgroups: sci.astro.planetarium Subject: SL9 bullet holes Date: 23 Jul 94 13:47:00 GMT Organization: MoonDog BBS Brooklyn, NY (718) 692-2498 I CAN SEE THE HOLES!!! -------------------- About July 10th the New York City Parks Department contracted the Amateur Astronomers Association to run a Moonwatch within the City's 25th anniversary festival of the Apollo 11 landing on the Moon. In working out the arrangments we called the Department's attention to the comet-Jupiter activity occurring in that same week. The AAA is the regional astronomy center for the New York City area. So the Association got the job of demonstrating both the Moon and Jupiter on Monday 18 July thru Wednesday 20 July 1994. On Monday and Tuesday we were the sole park event; on Wednesday we were part of the overall City celebration. Monday's session was cancelled for clouds and intermittent rain.. On Tuesday we deployed in Central Park's Sheep Meadow adjacent to Tavern-on-the-Green. Visitors could reach this spot from crosstown buses and the transit junction at Columbus Circle. Visitors could also nosh in Lincoln Square or Tavern-on-the-Green and then stroll over to the field. We set out a dozen telescopes, an info station, and two video monitors. Telescopists were armed with charts and factsheets. Much of the equipment and collateral crew was supplised by the Prks Department. The air was hot and hazy and humid, in the tradition of a New York summer. We announced the Moon landing festivites and noted that besides the Moon we will show Jupiter, upon which SL9 was right then snahing. However, we did caution the crowds against seeing actual damages from the collisions. After all we had only homesize instruments in the Sheep Meadow and the images already bannered on television were artificially puffed up. As the sky darkened we demonstrated the Moon and Jupiter on the video system. People could examine the screen for interesting features to see in the scopes. On the screen with Jupiter there were two dark and annoying dots near the south pole. They moved about with the planet as we corrected for drift. Uh oh. THEY WERE THE "BULLET" HOLES FROM THE COMET IMPACTS!!!! Word flashed up and down the telescope lines. The telescopists centered their instruments on Jupiter and let the populance look. Every one of the five thousand souls peeking thru the scopes gasped: "I can see the holes!!" There were two clear and obvious black dots -- like tiny eyes -- straddling the central meridian of the disc. After a while a one was centered and the other moved off to the west. They mimcked the shadow of a Jovian moon in transit across the disc. Every scope showed them from an 80mm refractor to a 320mm reflector. Every person on the lines saw them and walked away in amazement. Strangers clustered on the lawn around the scopes and animated about the dots. Many people promised to come back tomorrow to see them again. We prepared for a stay until 10ish based on the Park's schedule. But with the utter fascination from the stigmata on Jupiter the lines were full until 11:30PM. At that hour the Park managers asked us to wind things up and get some sleep [at home]. Wednesday the 20th there was a large setup of various exhibits for the anniversary. There was a projection screen for showing Moon related movies, concession stands, bicycle and skating tourneys, political speeches, party balloons, T-shirt and bead vendors, and other let's-have-a-be-in attractions. We established our stations and the hordes poured in. A good sprinkling of people heard from the newscasts during the day of the sighting of impact marks from Central Park the precious night! However, the sky was adverse right thru civil twilight with a blanket of clouds over all the sky. Yet there were enough thin sections to let the Moon and Jupiter shine thru. The folk who made the return visit were freaked out. THERE ARE MORE HOLES!!! Those seeing them for the first time were no less incredulous. THESE ARE THE BANGMARKS FROM THE COMET!!! Every one of the seven thousand visitors that night took long studied gazes at them. In deed, when we tried to show the Moon for a change, the crowds protested: "Nooo, leave the scope on Jupiter! We want Jupiter!!" As people walked away talking about their vision, others entering the Park overheard them and hurried straight to our stations! All over the field groups gathered to talk about the spots. They had newspaper articles and compared their view with the published ones. Some laid out on blankets for Jupiter picnics. Others brought binoculars to learn how to spot Jupiteer at home on other nights. Many hundreds of people after taking their look simply walked to an other telescope line and waited calmly for a second view! And so there was this grassroots outswelling of townsfolk on the broad lawns of Central Park, the peripheral trees, and enclosing 'stockade fence' of skyscrapers. As night fell the towers formed an all-around 'milky way' with their myriads of tinkling window lights. Above them danced the gibbous Moon and Jupiter amid the summer clouds. The other exhibits folded their tents starting at 9:30 and by 11:00 the Association was the only thing running in the Park! Finally at close to midnight the Park had to call it quits for the night. Nun aber zurueck zur Wissenschaft: Hier in Stichworten die letzte NASA- Pressekonferenz zum Thema: GSFC press conference 7/23/94 Don Savage- PR guy Heidi Hammel Melissa McGrath Eugene Shoemaker Carolyn Shoemaker David Levy Lucy McFadden Eugene S.: Last telescopically resolvable fragment hit Jupiter. Following wind still coming. Press said largest explosion in Universe. Actually only largest on planet. Heidi Hammel: This last frag. (W) has an assymetric plume, moved off to the side. Plumes from A, G, W, E have been seen by Hubble. Evolution of cloud features. Starting to spread out along the planet. A spot impact closeup is stretched into a line and starting to interact with normal Jovian (not great red) spot. Will look at Jupiter a week and a month from now to chart evolution. Melissa McGrath: Spectrum of impact site G on July 21, emission spikes from Magnesium, silicon, iron. We are seeing the cometary material. Monday observations show S2 ammonia, carbon disulfide absorption features. David Levy: Amateur from Jupiter Florida with 20" and CCD shows picture with two huge spots. 16" telescope shows details within spots. [Hat der geneigte Leser erraten, von welchem 16"-Teleskop David Levy hier live im TV gesprochen hat? RICHTIG: Er hat den im Kometenreport Nr.14 ab- gedruckten und ueber den Mailexploder verbreiteten ersten Bericht unserer eigenen Beobachtungen vorgelesen! S.H. rief eigens hier auf dem Berg an, um diesen bemerkenswerten Datenfluss Chile -> E-Mail -> TV zu melden...] Amateurs can keep spots straight by taking frequent images and recording times. G visible with 60 mm finder scope. Small telescopes make most apparent. Highlights? Hammel: fantastic images from Hubble, plumes, ripples, circulation, auroral arcs, sulfur, comet metals. But seeing first images of A impact. (Showed clip of astronomers getting excited) McFadden: SPIREX image composite shows 11 of 21 impacts. Kuiper: spectra from R,Q,W methane, acetelyne. IRTF video: evolution of fragment C: plume grows and decays, then rotates to front. Doyle Hall, Johns Hopkins, Extreme UV Explorer: significant brightning of Jupiter during impact, due to splash mixing of Helium gas upwards. Usually Helium is too deep. CINE comet impact network experiment: flash seen on Io during early fragment impact. 'Contractor for defense dept' Airborne Surveilence Testbed: 20" telescope on 767 on checkout mission. Viewed K impact. Highlights: everything together. Hammel: Images from Hubble are the result of hundreds of people. Give them a hand. McGrath: Future, we will learn about winds in atmosphere. Composition of atmosphere. Q&A Q: How many pictures have been taken Hammel: Hubble 400 McFadden: 900 by one instrument. Thousands of scientists on E-mail exploder. Q: Have you seen anything that might cause permanent effects? Hammel: too soon to tell. Wait and see. McGrath: Should be long-lived by Pinatubo analogy. Q: Why are spectral emissions surprising? Do they show something not obvious. McGrath: Hydrocarbons expected Instead saw sulfur and metals Eugene S: we have to catch a plane. I'll ask Carolyn what her favorite event was. Carolyn: Everything. Like proud parents. It belongs to the world now. Q: How many defined impact points have you identified? Does the following contain any large components? Could be unseen chunks, there will be dust. Impact sites have not been counted, Have not yet seen V, T, U, but haven't looked carefully at data. 18? 17? Small ground reports of T. Trailing wind will hit nearside. Q: how long will trail last? At least until end of Sept. Don't expect to detect anything. Expectations wrong in the past. Q: What instrument for the spectra, what wavelength scales? Faint object spectrograph. (UV?) No water, no oxygen. Ground shows hydroxyl. Q: How bad was traffic jam on infobahn? 126,000 downloads from STSCI. 4000 people simultaneously at Goddard. Q: How will you retract if instant science wrong. Hammel: That's the process of science. If it's wrong, it will be corrected. We will get a coherent story with all data together. Q: Why surprised to see molecules from comet? Have we had confirmed flash on Io? Reta Beebe's bubble different from fireball? McGrath: we are surprised to see sulfur molecules. Expected to see carbon and hydrogen. McFadden: David Rabinowitz sees reddening of spectrum from Io. Confirmed. Unexpected result that only see that one. Hammel: Plume thrown up beck along path, transient. Reta hopes to see energy deposit at explosion point causing hot gas upwelling creating a surface feature. Q: Will you be mounting a campaign to llok for other planet collisions? Any specific plans for Galileo or post-Galileo? Hammel: we look at planets, but impacts are rare so we won't be searching, unelss we see a comet heading towards a planet. Hammel: I'm not on Galileo team. They will certainly look. Q: how do you know metals are from comet? Why didn't see before? Didn't see them before because continuum too high. The comet and Jupiter have same overall elemental abundance but the metals have sunk to the center of Jupiter. Q:Radio? Ari Grossman et al. at VLA looking at ammonia clouds, see no evidence of perturbations. Ulysses has no significant detections. Voyager Ultraviolet spectro shows no significant detection. Decametric and Decimetric (synchrotron) radiation shows no changes greater than what you normally get. Q: Size of fragments A few kilometers. Should get a better estimate. Q: Seismic waves? Telescope looking for seismics clouded out mostly. Data hard to analyse. Be patient. David M. Palmer palmer@alumni.caltech.edu Offenbar werden nicht nur hier die Jupiterbeobachter zunehmend von den 'normalen' Astronomen verdraengt - aber manchmal gibt es noch ein klei- nes Fenster, wie die Infrarotbeobachter vom Palomar Mountain berichten: Thanks to the courtesy of the scheduled observers, and the observatory director, we are continuing to monitor Jupiter under perfectly clear skies (too late, alas for impacts F=20 and L!) at 2.0-4.0 um and at 8-14 um. We are happy to report that most of the spots are still alive and well. At 10 um we continue to see significant emission from sites G/S/R (bright and extended 5" EW with a sinuous appearance), Q (faint), H, K/W/U (about twice the surface brightness of Jupiter, and=20 extended to the S) and L (very bright, especially on the limb). Some of the spots are now sufficiently extended EW for us to=20 resolve spatial variations in their 8-14 um spectra. We are also obtaining regular sequences of narrowband CVF images between 2.0 and 2.35 um, and between 3.0 and 4.0 um. At these wavelengths, spots G/S, R, Q1, H, E, A, C, K/W and L continue to be extremely prominent, especially at 2.35 um. On July 24, at 5:00 UT, a small feature was visible slightly south of Q1 and R, but located midway between them in longitude. A possible candidate for Q2, perhaps? Features G/S, H, K, and L are very extended, each with a distinctive shape which varies systematically with projection effects across the disk. K still shows a bright NW core, with a long curling 'tail' shaped like a ? on its side, open to the south. G, H, E and L all show prominent extensions toward (jovian) east. Only the fainter R, Q1, A, and C spots look more or less circular, although none of these images has been subjected to any analysis as yet. We are too busy filling Exabyte tapes! Current count is well over 3000 near-IR images over the last 11 days. No impact site that we have ever detected has disappeared, and it is not clear that they have even faded. Tonight we hope to see site A on its 21st rotation; a fitting farewell to Jupiter and SL9. Paul Chodas visited the telecope last night, and was able to see for himself the damage his babies have wrought. Phil Nicholson, for The (almost exhausted) Palomar observing team. Und im Ultravioletten ziehen die IUE-Beobachter ihre ersten Bilanzen: IUE OBSERVATIONS SUMMARY: UPDATE 21 JULY 1994. European space scientists cointinue with their American colleagues in the 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/UK), 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). Such results can only be obtained from space since the ultraviolet range is inaccessible to ground based observatories. Observations of the Jupiter system have been performed with the IUE satellite on a 24 hour basis since the 15th of July, and intermittantly since early June. The IUE imaging spectrographs have a combined spectral coverage from 1150- 3300E at resolutions from .14 to 6E. We are monitoring several of the best studied upper atmospheric features of Jupiter and its magnetosphere including the Aurora, the Ly-alpha equatorial anomaly, and the Io torus. We have detected changes in some of these features (in particular, the aurora has been weak) that we attribute to (or at least find suspiciously coincidental with) the effects of the comet fragment impacts and/or to the passage of dust through the inner Jovian magnetosphere. The IUE is also being used to monitor the development of spectral features in the impact areas, and in particular has been useful for showing the timescales that describe the development of the dark features seen in the WFPC-II images. The A, B, E, G, K, and Q impacts have been observed wiht great success. SPECTRA OF PLUMES ASSOCIATED WITH IMPACTS 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. Dr. Walt Harris (Un. of Michigan, USA), also a memeber of the ESA/NASA IUE Science Team reports that the analysis of spectra obtained on the approaching and receeding limb while we followed the G impact site with the IUE small aperture show that the region experienced a 50% drop in reflectivity as it rotated moved across the disk of the planet. Many possible absorption and emission features have also been observed in spectra obtained from the impact sites. 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 and 330 nm Both features were short-lived and had disappeared after a few hours. The identification of the absorption 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 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 exploded material of the cometary nucleus and the destruction of the Comet nuclei takes place well above the Jupiter cloud layer. This would also be suggested by the tentative identification of the 330 nm emission with the unexpected presence of a possibly Sodium (Na). ABSENCE OF REFLECTION PULSES OF THE IMPACT FLASH Shortly before the spectra, observations are made with IUE to detect the predicted brightening of the Jovian satellites in response to the flash of the direct impacts, which are all taking place on the backside of Jupiter. Europa was used as a mirror to look behind Jupiter. No noticeable brightening at the 1% level was observed until now. This will considerably constrain the possible models for the phenomena associated with the direct impact. LY-ALPHA IMAGING OF IMPACT PLUMES Dr. Gilda Ballester (Univ. Of Michigan, USA) reports for the IUE ESA/NASA observing team the likely detection of Lyman alpha emission of atomic Hydrogen off the Jovian limb associated with the plume of the impacts of fragments K, and P2 using the modest imaging capabilities of the IUE Space Observatory satellite. Although the Point-Spread-Function (i. e. spatial resolving power) of IUE at Lyman-alpha is 4-5 arcsec and IUE has no two dimensional direct imaging capabilities , the emission can be seen to peak near/at the limb. There is also quite extended,weaker emission within the large (9x21 arcsec) aperture, extending possibly out to 3-4 arcsec above the limb. Molecular hydrogen emission has also been detected (possibly less extended than the atomic H-Lyman alpha, although this needs to be confirmed by a more extensive analysis later on). Also impacts Q and R have also been observed but not imaged with the small (3 arcsec) aperture. The ESA/NASA studies with IUE will continue to monitor the effects of the impacts on a 24 hour basis with the IUE until the end of the week, and then on a less regular schedule until it becomes unobservable with the IUE Space Observatory on Aug. 15. LY-A IMAGING OF IMPACT PLUMES: REPORT FROM GILDA BALLESTER. We report on the likely detection of H-Lyman alpha emission off the Jovian limb associated with the plume of the impacts of fragments K, and P2 using the modest imaging capabilities of the IUE satellite. Although the PSF at Lyman-alpha is 4-5 arcsec, the emission peaks near/at the limb, and there is also quite extended,weaker emission within the 9"x21" aperture possibly 3-4 arcsec above the limb. Some molecular hydrogen emission is also detected (it appears less extended compared to the H-Lyman alpha, although this could be the effect of low S/N). Impacts Q and R have also been observed but not imaged with the small 3" aperture. Gilda Ballester for the IUE US-Vilspa observing team. REPORT FROM WALT HARRIS (IUE US SCIENCE TEAM ) 21 JULY 1994. Observations of the Jupiter system have been performed with the IUE satellite on a 24 hour basis since the 15th of July, and intermittantly since early June. The IUE imaging spectrographs have a combined spectral coverage from 1150-3300A at resolutions from .14 to 6A. We are monitoring several of the best studied upper atmospheric features of Jupiter and its magnetosphere including the Aurora, the LY-a equatorial anomaly, and the Io torus. We have detected changes in some of these features (in particular, the aurora has been weak) that we attribute to (or at least find suspiciously coincidental with) the effects of the comet fragment impacts and/or to the passage of dust through the inner Jovian magnetosphere. The IUE is also being used to monitor the development of spectral features in the impact areas, and in particular has been useful for showing the timescales that describe the development of the dark features seen in the WFPC-II images. The A, B, E, G, K, and Q impacts have been observed wiht great success. For instance, our analysis of spectra obtained on the approaching and receeding limb while we followed the G impact site with the IUE small aperture show that the region experienced a 50% drop in reflectivity as it rotated moved across the disk of the planet. Many possible absorption and emission features have also been observed in spectra obtained from the impact sites. We have not as yet had an opportunity to analyze these features properly. We are also performing an unprecedented number of simultaneous observations with other instruments. This is providing new insight into the characteristics of features long studied with the IUE, and gives the operators of the other instruments an opportunity to compare the results of their observations with the more than 15 years of Jovian FUV spectra in the archives. Along with our European collaborators, we will continue to monitor the effects of the impacts on a 24 hour basis with the IUE until the end of the week, and then on a less regular schedule until it becomse unobservable with the satellite on Aug. 15. Walt Harris; for the IUE US science team 7/21/94 Unterdessen gibt es eine Kontroverse, ob die angeblichen Riesenringe um einige Einschlagstellen echt sind oder nicht: Groundbased versus Space Telescope ... LARGE RING OBSERVED ON JUPITER A very large dark ring is seen surrounding the impact site which moved onto the limb at about 10:02 UT 21 July. (perhaps the L site?) The ring extended beyond the south pole, and nearly to the equator, imaged using a Bessell blue filter and CCD detector. The central impact site was also dark in this filter. Where this ring intersected Jupiter's dark band at about 20 degrees south latitude (belt? zone?) the methane image shows a bright spot. The impact site is not bright in the methane (8900 A, 300 A wide) This complex was seen to move across the face of the planet in successive images taken between 9:24 and 10:38 UT. By 12:46 poor seeing prevented seeing it. This feature was marginally visible in a narrowband sodium filter, but not in a Cousins R filter. These observations are part of the Comet Impact Network Experiment headed by Steve Larson of the University of Arizona. Ellen Howell Mount Stromlo Siding Spring Observatory 1m telescope Images obtained from Lick using a high speed CCD camera system on 20 July UT confirm the reports of Howell and others from Mount Stromlo that there is a possible large dark ring surrounding the A impact site. We observed the impact sites using a variety of filters (bandwidth 100 A). In B images obtained from 04:00 to 05:00 UT (July 20), we observe a large dark arc-like structure extending from the south pole up to -20 degrees S latitude and centered on the A impact site (which was also dark in our B images). The arc has a radius of roughly 10 arcsec. The structure is also visible in our U band images but is not visible in any of our narrowband filters. There are at least two immediately obvious possible explanations for this feature: (1) it may be the visible expression of an expanding shell (or wave) of material from the A impact site: the feature is large because the A site is oldest; (2) it may be an artifact introduced by a combination of 2-arcsec seeing and the fortuitous alignment of the GRS and H impact site along an annulus concentric to the A site. In the exploder report by Howell, the bright spot in the methane filter at the intersection of the dark ring and Jupiter's dark -20 degree band is probably the GRS. Also, the impact site on the dawn limb in the Howell image is most likely the A site. Jupiter's aspect was nearly the same at 04:00 UT on July 20 and 10:00 UT on July 21. Jim Bell, Ted Dunham, Dominique Toublanc and Bob Thompson Lick Observatory Crossley 36-inch Observing Team, USA. Re antipodal features: Based on the timing provided by Spencer et al., the dark feature they report appears to correspond to a dark wave-like structure along the south edge of the North Tropical Zone. It was prominent in our pre-impact images.=20 It is probably not related to the impacts. Re evolution: Features are clearly being rapidly sheared and spread by Jovian winds. Looks like "one heck of a mess." :-) Re large rings: We still see no evidence for large rings in Hubble imaging at any wavelength (aside from the ejecta veils, which are more visible when near the limbs of the planet). However, we do not have continuous temporal sampling. More careful timings from those who have reported them would help us to verify their existence. Other notes: Q2 and N sites are so small that they are difficult to detect in our Wide Field images (0.1 arcsec/pixel). Heidi Hammel, for the Hubble Space Telescope Comet Team Etwas spaet treffen immer mehr Beobachtungsberichte aus der GUS ein, so von Organization: Special Astrophysical Observatory RAS From: Gera Chuntonov Date: Sat, 23 Jul 94 07:52:05 +0400 Subject: Observational report from the Zelenchuk observing team Belgo-Franco-Russian team tentatively observed the W impact between 1900 and 1930 UTC using a Fourier spectrometer working from 2400 to 3000 cm-1 at a 0.25 cm-1 resolution. Observations were performed at the SAO 6-m telescope located in North Caucasus. A CCD camera provided impact and spot monitoring. The intense spot at the site of impact W was observed 11 hours after crash. It is not easily separated from those of U and K. Its general shape is seen as a diffuse circular dark spot as large as 3.5 arcseconds. The reduction of spectral data will be made later. Unfortunately, bad weather prevented other observations at this date except on July 19. C. Muller, D. Moreau (BISA, Brussels) M. Cuisenier, K. Hammal, J. Rosenqvist (Obs. Meudon) I. Balega, G. Chuntonov, G. Dolnikov, I. Maslov (SAO/IKI) Das Interesse richtet sich jetzt auch auf: Meetings about the impact I know of the following meetings about the SL9 impact into Jupiter. I would appreciate it if anyone knowing of other meetings could let me know about them by sending email to the c1993e account at Maryland. We will send out a more complete summary over the exploder after we have heard from other people. August 1994 A special session to be held at the IAU General Assembly in The Hague. This session is being organized by the officers of Commmissions=20 15 and 16. November 1994 A special session will be held at the Annual Meeting of the Division for Planetary Sciences of the AAS in MarylanD. February 1995 A special session will be held at the annual meeting of the AAAS in Atlanta. May 1995 A major meeting will be held at the Space Telescope Science Institute in Baltimore. This will be their annual May symposium. Sponsorship as an IAU Colloquium has been requested. Mike A'Hearn Und einer faengt jetzt an, 'human interest stories' zu SL9 zu sammeln: Observers, Now that it's all over, and before you pack up to leave your telescope, would you be willing to share some of your thoughts and emotions and adventures you had while observing? What is your overriding feeling as the observing draws to a close? What, if anything, did you think about earth while watching? Were there crises and dramas before or during your data taking? For example, we read that at the South Pole someone braved icy conditions to remove snow from the telescope so that observing could begin. What about the rest of you? If you're willing to contribute, I think we could end up with a wonderful collection of material that will show what scientific research is really like, and how scientists from all over the world shared in this adventure. You're comments may be published. I am working on a book on Impacts and an article about the experience of observing the impacts via internet. I just realized that neither would be complete without hearing from you to add another dimension. So take this experience to its logical conclusion and share your final thoughts via e-mail as if I was interviewing you personally and let's see where it leads. Thank you all in anticipation. It's been wonderful reading your reports, all of them. Gerrit L. Verschuur SKY & TELESCOPE'S NEWS BULLETIN -- JULY 23, 1994 COMET IMPACTS OVER? It's over. Or is it? The last known chunk of the comet, W, hit Jupiter around 4 a.m. Friday morning Eastern time. But smaller debris that was in the comet's southwestern tail will keep plowing into Jupiter for weeks. Moreover, after July 27th, this stuff will hit on the NEAR side in full view from Earth. Any good-size chunks might cause visible flares. The most pieces, and the largest ones, should come soonest. The debris will grow sparser, and the pieces smaller, as days and weeks go by. The material will keep hitting near the celestial east limb at sites gradually moving north. So keep Jupiter under watch, and be ready to note the time to the second if you see a definite flare. And, of course, there are still the black spots! Spot A is already fading, suggesting they may last only a few more days. Get 'em while they're hot. Some spots have been much bigger, darker, and more visible than others. Big ones to watch for include H, K, L, and the G-S-R-Q complex. Detaillierte Transitvoraussagen aus Norwegen - exklusiv nur bei uns... : [...] Und GANZ zum Schluss noch die Antwort auf DIE Frage, die alle Kometen-Fans nun bewegt: Wie wird man mit dem Verlust von gleich 21 aufeinmal fertig, die man auch noch selbst entdeckt hat? In den ABC News gab's am FR die Antwort: From: Richard C. Bareford Subject: ABC News Chooses SL9 Team Its Persons of the Week Last night (22 July 1994) ABC News recognized Eugene and Carolyn Shoemaker, and David Levy as their Persons of the Week. In a remarkably well done piece each co-discover was afforded the opportunity to state complete thoughts! There was a good selection of SL9 imagery and scenes of the team at work on the Schmidt camera at Palomar. The significance of their accomplishment was intelligently presented along with interesting personal information. There was even a strong plug for amateur astronomy! I noticed no inaccuracies or misconceptions in the narrative. The piece ended with a touching revelation. Carolyn proudly displayed the necklace Gene had given her to replace the "string of pearls" she had lost on Jupiter. Very nice. No kidding! In diesem Sinne: Bis zum naechsten Kometencrash, Euer Daniel Fischer