The next MEPCO is coming ... to Bulgaria, in early August, 1999!
For details on this astronomical conference just before the total solar eclipse click here!

The 1998 Leonids: What really happened Surprises are the rule when it comes to meteor streams, and the Leonid meteors of 1998 were no exception. The big storm of thousands of (largely faint) meteors that was expected for Nov. 17 around 20 hrs UTC never materialized. But instead there was a - possibly unique - prolonged firework display of mostly very bright meteors visible the night before. Because it lasted for many hours it was visible not only from Eastern Asia, where many of the world's leading meteor experts had travelled, but also from Europe and Northern America. At first the actual numbers of meteors seen in the sky were confusing - especially one report from the Canary Islands that claimed a hourly rate of up to 2000. While this number is still being quoted (e.g. in the Nov. 28 New Scientist), it's plain wrong. The astronomer who reported the number (which was quickly distributed by the R.A.S. and the IAUC's) soon admitted that he had no idea how to do a valid meteor count: He had thrown together counts from half a dozen people and then extrapolated... The generally accepted method to determine the meteor rate, however, is to use counts by single observers, which can later be corrected for geometrical effects as well as the sky quality to yield the famous ZHR, the Zenithal Hourly Rate. These values are the "meteor rates" quoted all over the literature, and they roughly correspond to what a single, dark-adapted observer sees in a dark, unobstructed sky, when the meteors' radiant is high. The real meteor rates According to the Nov. 26 analysis of visual counts from many observers around the world by the International Meteor Organization, "the ZHR profile shows a broad maximum centred at solar longitude 234.5 (Nov 17, 01h30m UT) with an average ZHR of 260. The full width at half maximum is about 16 hours. The 'storm component' exhibits an enhancement at the declining part of the background activity. The peak time of this component lies between 235.3 and 235.4 (Nov 17, 20h20m and 22h30m UT)." 'Background activity' refers to the bright meteors that surprised many during the night of Nov. 16/17: These are caused by large dust particles that comet Tempel-Tuttle has lost centuries ago, and there is some evidence that a similar "early" background was seen in 1965 (the year before the Leonids mega-storm). The 'storm component' consists of faint meteors, caused by small dust particles lost recently by the comet. It was hardly evident at all and only showed up clearly in the IMO analysis of thousands of individual meteors. As the timing of this enhancement shows, it appeared within a few hours of the predicted possible storm: Therefore it is wrong to say that "the 1998 Leonids came 15 hours too early"! But it cannot be denied that nearly all model calculations have been way off: Unisono they predicted ZHR's of at least 200 and possibly up to and beyond 10 000 around 20 UT on Nov. 17, while at the same time not one study explicitly predicted a major background component 15 hrs earlier. The Leonids still made history Even without the anticipated meteor storm, the 1998 Leonids are stuff for the (astronomical) history books - the prospect of a major celestial event had spurned a number of unique scientific as well as operational actions: For the first time the intensity of a meteor shower has been measured and made available in real-time to satellite operators. For this purpose a joint Canadian-U.S. venture sent expeditions to two sites in Mongolia and one in Australia, to record the ongoing activity visually, by video and (in Australia) by radar. The observations were forwarded to Canada and the U.S. several times an hour. Satellite operators all over the world took precautions for the possible meteor storm, such as powering down sensitive instruments on science satellites (e.g. on SOHO) or turning spacecraft into less exposed attitudes (such as Hubble). Also specialists were ready to take more drastic steps if abovementioned real-time network would have sent out alarm messages. Because the Leonids are the only meteor stream known to cause storms now and then that can be predicted with some reliability (or so it seemed until Nov. 17, 1998 :-), many science operations were underway during maximum time. Most notably: Several airplanes carrying IR and UV equipment were flying over Asia. And a high-altitude ballon was launched over Georgia, U.S.A., with an aerogel collector to collect a raw Leonid particle or two. The Mir cosmonauts had mounted a similar device to the outside of Mir, for later collection. So - what are the prospects for 1999 and 2000? Even after their bad luck this year, all experts are still optimistic that the 'storm component' will be there again in 1999, possibly stronger than in 1998 (when it barely reached a ZHR of 120): It would be seen best from Europe. And regarding the background component that brought so many wonderful fireballs, all bets are off...	Here is a detailled report from Mongolia and the big expeditions! And here is an early report from there (Canadian mirror). While this is the 'official' IMO analysis of visual observations around the globe. Here are some links relating to the Canadian part of the Mongolian action: 1, 2, 3, 4, 5. Here is one on the Australian radar. And here are three relating to the U.S.(A.F.) part: 55th Space Weather Sqdr. (where the data came together), S.P. Worden (who represented the U.S.A.F. in Mongolia) and something on Worden. The best pictures were found at Modra Obs., Slovakia (a wonderful fish-eye view with 150+ Leonids), ROTSE, New Mexico (animGIF of a meteor train) and a special NASA site (check out the earlier stories there, too!) Early reports to S&T. Some Leonid expedition news and other reports: The results from IMO's ALEX'98 (Mongolia), DMS (China), Staiger (Thailand), JAS (Jordan), ESA (Netherlands), Parkes Obs. (Australia), Airborne observations (Ames/Japan; there is also a meteor spectrum from the mission) What the HST did. Media coverage of remaining interest: BBC Nov. 26 (see also the other stories), ABCNEWS Nov. 24, Toronto Star Nov. 23, CNN amd RP of Nov. 18, CNN, ABC and Astr. Now of Nov. 17. Yahoo U.S., Yahoo D, Chiang Mai News General Leonids pages: Leonids Live from NASA, ESO, SpaceViews, News from the ongoing data analysis For historical interest: Predictions from Yeomans (who claims he was right in Space News of Nov. 23 - see for yourself) and STK
ISS' assembly under way After the successful Proton launch of the first International Space Station element "Zarya" on Nov. 20, NASA program managers on Nov. 24th set Dec. 3 as the official launch date for the STS-88 mission aboard Space Shuttle Endeavour. This is the first Shuttle mission dedicated to the assembly of the ISS. The six-member flight crew will work to mate Endeavour's primary payload, the U.S.-made Unity connecting module, to the Russian-built Zarya control module during the 12-day mission. While the STS-88 Flight Readiness Review was in progress, Russian flight controllers performed tests on Zarya's onboard systems and adjusted its orbital altitude. Endeavour is scheduled for launch Dec. 3 at about 3:59 a.m. EST from Launch Pad 39A. The exact launch time will be determined during the final hour of the launch countdown as mission controllers pinpoint Zarya's exact orbital position. The mission is slated to last 11 days, 19 hours and 49 inutes. An on-time launch will lead to a Kennedy Space enter landing on Monday, Dec. 14 at 11:48 p.m. EST. The STS-88 Mission Commander is Robert Cabana. The pilot is Fredrick Sturckow. Nancy Currie, Jerry Ross, James Newman and Russian cosmonaut Sergei Krikalev will serve as mission specialists on this flight. (Adapted from KSC Release No. 143-98)	Vital Stats of the ISS (German) ISS page The ISS Early Launches Press Kit: parts 1, 2, 3, 4, 5. Information on the first two elements, Zarya and Unity Lauch of Zarya The ATV Here's what the space shuttle orbiter Discovery looked like after STS-95.
A good month for optical astronomy is coming to an end: November 1998 saw, for example, the release of Hubble's observations of the Hubble Deep Field-South which resembles - as expected - the Northern HDF. This area in the sky promises to become one of the most-studied in the sky. First Light for the 2nd science instrument of ESO's Very Large Telescope, ISAAC. This powerful Near-IR camera was installed on Nov. 14 - and promptly delivered striking images. the certification of the mirror of the Japanese Subaru telescope. Another 8 m class instrument will now soon have its nights in the starlight. In other ESO News, a new search program on La Silla has promptly discovered a new exoplanet.	HDF-South: STScI Press Release, HDF-S Homepage. VLT News: ISAAC's first pictures, more FORS images, an overview of the science verification observations with the test camera, a nice image of Jupiter. Subaru: Homepage.

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Compiled and written by Daniel Fischer
(send me a mail to dfischer@astro.uni-bonn.de!), Skyweek