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This page was last modified on November 10, 1999 by Casper ter Kuile, Carl Johannink, Hans Betlem |
Info on the Leonids '99
By the International Meteor Organisation (IMO)
The 1999 Leonids
Dear Meteor Friend,
There is no need for telling you that this year's Leonids may well produce very high activity, most likely over European longitudes, as the most probable peak time is around 3h UT on November 18, 1999. For your information, we provide you in attachment with the following documents:
- Press Release;
- Science Note;
- Visual Observing Hints.
In case a meteor storm materializes, it is no longer possible to record all observing data a visual observer usually records, and, therefore, you must make priorities. Document 3 is all about choosing these priorities in such a way that later analyses can get the most out of your observations, so we strongly urge you to study this! It is a reprint of an article that appeared in the October 1999 issue of WGN.
Furthermore, it is not unlikely that your local press may ask you for information about the upcoming Leonid event. For this purpose, Documents 1 and 2 (a short press release and more expanded elaboration) may be useful. Provided proper credit is given, you are welcome to use these documents in any manner that suits you.
Finally, note that the International Meteor Organization is currently making arrangements to ensure, weather permitting, that reliable first results will be available within hours after the above time. A press release based on these results will also be forwarded to you.
Kind regards,
Marc Gyssens
Council Memberemail: wgn@imo.net
phone: +32-477-64 05 48To unsubscribe from IMO-News, send a blank message to imo-news-unsubscribe@egroups.com, or visit www.e-groups.com/list/imo-news.
Press release
Night of November 17-18:
strong activity of Leonid meteors expected
From most of Europe, the Mediterranean area, and northern Africa, people may see a lot of meteors - "shooting stars" - between midnight and dawn of the night of November 17 to 18, provided skies are clear. These meteors belong to the so-called Leonid shower. The peak of this shower is expected around 2 a.m. Greenwich Mean Time, which is 3 a.m. local time for most of continental western and central Europe and mid-northern and west-central Africa, and 4 a.m. local time for eastern Europe, Turkey, Israel, Jordan, and northeast Africa. At that time, an observer will see at least 50 to 100 meteors per hour, but there is a fair chance that a veritable meteor storm will materialize with 1000 or more meteors per hour around the abovementioned time. The International Meteor Organization, who collects meteor observations world-wide for the purpose of analysis, wishes to point the attention of the public to this spectacular natural phenomenon.
The Leonids are caused by a stream of predominantly very small particles, less than 1 mm in size, which orbit the Sun with a period of 33 years, together with their parent comet, Tempel-Tuttle. The orbit of the Leonid particles happens to intersect the Earth's orbit. Each year around November 17, when the Earth is at this intersection, Leonid particles may enter the Earth's atmosphere and cause meteors, popularly called "shooting stars." This year, around 2 a.m. Greenwich Mean Time, in the morning hours of the night of November 17 to 18, the Earth will pass through the outer regions of a dense dust trail of Leonid particles ejected by Comet Tempel-Tuttle 100 years ago. Comparison with similar events in the past results in an expected activity of around 500 or 1000 meteors per hour around the abovementioned time, but these numbers are only indicative: the real frequency may be both higher or lower! However, even if the storm would fail to materialize, a frequency of 50 to 100 meteors per hour is guaranteed. Should Leonid meteor activity disappoint in 1999, it is good to know that Leonid meteor storms are possible in 2000, 2001, and 2002, too!
Actually, Leonid meteors can be seen every year around November 17. Along the larger part of Comet Tempel-Tuttle's orbit, however, Leonid particles are scattered sparsely, so that, in most years, we see only a few Leonid meteors per hour. Only in the vicinity of the Comet, the density of Leonid particles is much higher. Therefore, we observe much higher Leonid activity every 33 years during a couple of years, when Comet Tempel-Tuttle revisits our region of the Solar System. In some instances, we even see a real meteor storm!
Old chronicles contain references to past Leonid meteor storms back to the 10th century A.D. The best-known Leonid meteor storms are those of 1833 and 1966, when tens of meteors per second darted across the skies during the peak hour! The 1833 meteor storm was so spectacular that it in fact launched meteor research as a branch of astronomy. Since the 1966 meteor storm, Comet Tempel-Tuttle has completed another revolution around the Sun. The passage of the Comet through its closest point to the Sun on February 28, 1998 marked the beginning of a five-year period (1998-2002) during which strongly increased Leonid meteor activity is again possible.
In 1998, a meteor storm did not materialize around the expected peak time. The night before, however, saw an unexpected shower of very bright meteors and fireballs. Astronomers managed to figure out what had happened, and new computations match past Leonid meteor storms so closely that there is good hope that the most recent predictions for the period 1999-2002 are reliable.
The expected activity of Leonid meteors can in principle be seen from any place in the abovementioned part of the world. Of course, the sky must be clear and the selected observing site should preferentially be free of light pollution; the less light, the more meteors will be seen! Leonid meteors cannot be seen before around midnight. Hence, there is no point in starting an observation earlier. Die-hards who do not want to miss anything of the show should then continue to watch until dawn. People who cannot afford to stay up that long should focus on the period between 1:30 a.m. and 3 a.m. Greenwich Mean Time.
Mind that it can be very cold in mid-November: warm clothing adapted to the local climate is essential! For comfortable observing, use a reclining chair, and install yourself in a suitable sleeping bag or under several blankets. While observing, do not fix a particular star, but look relaxedly and patiently to a wide area of sky and wait for shooting stars to appear.
More information on the Leonids can be found in the International Meteor Organization's bimonthly journal WGN and on the internet, at http://www.imo.net.
For questions, contact Marc Gyssens at wgn@imo.net or +32-477-64 05 48.
Notice that the International Meteor Organization will send out a new release with first results on the Leonids during the European early morning hours of November 18, immediately after the event. All recipients of the present release will automatically receive the new release.
To unsubscribe from IMO-News, send a blank message to imo-news-unsubscribe@egroups.com, or visit www.e-groups.com/list/imo-news.
Science Note
Night of November 17-18:
strong activity of Leonid meteors expected
SUMMARY - From most of Europe, the Mediterranean area, and northern and west-central Africa, people may see a lot of meteors - "shooting stars" - between midnight and dawn of the night of November 17 to 18, provided skies are clear. These meteors belong to the so-called Leonid shower. The peak of this shower is expected around 2 a.m. Greenwich Mean Time, which is 3 a.m. local time for most of continental western and central Europe and mid-northern and west-central Africa, and 4 a.m. local time for eastern Europe, Turkey, Israel, Jordan, and northeast Africa. At that time, an observer will see at least 50 to 100 meteors per hour, but their is a fair chance that a veritable meteor storm will materialize with 1000 or more meteors per hour around the abovementioned time. The International Meteor Organization, who collects meteor observations world-wide for the purpose of analysis, whiches to point the attention of the public to this spectacular natural phenomenon.
[Numbers between brackets refer to the glossary section.]
- THE LEONIDS
The Leonids are caused by a stream of predominantly very small particles, less than 1 mm in size, which orbit the Sun with a period of 33 years, together with their parent comet (1), Tempel-Tuttle. The orbit of the Leonid particles happens to intersect the Earth's orbit. Each year around November 17, when the Earth is at this intersection, Leonid particles may enter the Earth's atmosphere and cause meteors (2). Along the larger part of Comet Tempel-Tuttle's orbit, Leonid particles are scattered sparsely, so that, in most years, we see only a few Leonid meteors per hour. Only in the vicinity of the Comet, the density of Leonid particles is much higher. Consequently, every 33 years, during the years that Comet Tempel-Tuttle revisits our region of the Solar System, much higher Leonid activity is recorded. In some instances, this Leonid meteor shower develops into a real meteor storm!
- LEONIDS IN THE PAST
Old chronicles from all over the world (European, Arab, Chinese, Korean, Japanese, American, ...) contain references to past Leonid meteor storms back to the 10th century A.D.
Well-documented observations of Leonid meteor storms go back only to 1799, when the great German explorer and naturalist Alexander Von Humboldt, rather coincidentally, witnessed a Leonid meteor storm from Venezuela. The same spectacular phenomenon was also observed from Florida.
However, the 1833 Leonid meteor storm had a far greater impact on the public and the scientists alike, mainly because it was visible in a much more densely populated area, namely New England. At its peak, tens of meteors crossed the sky each second! Pious Christians believed that Judgment Day had broken and many who witness this celestial fireworks compared it to a snow storm! Because of the interest it had sparked, this particular Leonid meteor storm turned out to be very instrumental for the development of meteor astronomy.
A somewhat less spectacular Leonid meteor storm occurred in 1866; around 1899 and 1933, there was increased Leonid meteor activity, but no storm.
In 1966, however, the Leonids returned in full splendor: observers at Kitt Peak in Arizona saw a Leonid meteor storm peaking with no less than approximately 40 meteors each second, which amounts to a frequency of 150 000 meteors per second!
- LEONIDS TODAY
Since the 1966 meteor storm, Comet Tempel-Tuttle has completed another revolution around the Sun. The passage of the Comet through its closest point to the Sun on February 28, 1998 marked the beginning of a five-year period (1998-2002) during which strongly increased Leonid meteor activity is again possible. Whether or not a meteor storm actually materializes in any or all of these years depends on several circumstances, on which we will briefly elaborate.
- WHEN DO STORMS MATERIALIZE?
Meteor showers (3) are caused by small particles orbiting the Sun, in most cases released by comets. Each time a comet passes the Sun, it releases "dust" particles (as well as gasses), in the case of Comet Tempel-Tuttle every 33 years. As a first approximation, we may compare this dust production to the condensation trail of a jet plane. Like a condensation trail, a dust filament released by a comet fades away over a period of a few centuries until it can no longer be distinguished from the dust around the comet that was released much longer ago. Only if the Earth passes through a dust particle filament released by the comet at most 7 or 8 revolutions ago, in the case of Comet Tempel-Tuttle less than about 250 years ago, will a veritable meteor storm occur.
Every 33 years, when the Comet passes the Sun, there is a "window" of about 5 years in which the Earth may pass through one or more "young" dust particle filaments. When this happens, we see a storm of between about one thousand and more than one hundred thousand meteors per hour, lasting at most one hour. The actual peak of the activity is often of even shorter duration. The precise frequency depends on the age of the filament and whether the Earth goes straight through the core of this filament, or only through its outer regions. If the Earth misses all young dust particle filaments, the older dust particles around the comet will give rise to a more modest meteor shower producing 50 to 100 meteors per hour.
- WHEN DO WE SEE LEONID METEORS?
Around November 17, Leonid particles may enter the Earth's atmosphere from a direction - called the radiant (4) located in the head of the constellation of Leo, the Lion, from which the shower derives its name. Because Leo is below the horizon in most of the first half of the night, we can only see Leonids past midnight. From one particular location, a possible Leonid meteor storm is only visible if peak activity occurs between midnight and dawn. In addition, you need a clear sky, which is not for granted around mid-November ...
- WHAT HAPPENED IN 1998?
During the first morning hours of November 17, 1998, early birds witnessed a veritable fireball (1) storm: during a typical hour, 100 to 200 very bright meteors appeared. These meteors were even so bright, that the spectacular show could be followed well into dawn. During the night of November 17 to 18, when peak activity was supposed to occur, many casual observers around the world saw nothing at all ... a "miscalculation" of the astronomers, as some reported?
The fireball storm in the morning of November 17 came as a complete surprise. Later calculations showed that large dust particles released by the Comet 6 to 7 centuries ago were responsible for this phenomenon. Normally, dust particle filaments that old have completely faded away and are incapable of producing significantly enhanced activity. In this case, astronomers have shown that the gravitational pull of the giant planet Jupiter managed to keep at least the larger dust particles together. Other forces cause the smaller dust particles to disperse much more easily than the larger ones - this explains why so many fireballs and so few weaker meteors were seen.
The "actual" storm - if at all a storm were to materialize - was expected on November 17 around 8:30 p.m. Greenwich Mean Time. At that time, it was early afternoon in the Americas, while Europe and Africa were in the first half of their night of November 17 to 18. Hence, it was impossible for the people on these continents to see a Leonid meteor storm there, but this message failed to reach many of them, causing disappointment that could have been avoided. Central Asia, however, was in the second half of its night of November 17 to 18, and several observers have set up expeditions to China, Mongolia, and Siberia. Unfortunately, a meteor storm did not materialize. At their peak, the Leonids showed no more than 100 to 150 meteors per hour. Later calculations revealed that the Earth had missed all young dust particle filaments.
- WHAT MAY BE EXPECTED THIS YEAR?
The calculations made after the 1998 Leonid event referred to in the previous paragraph and comparisons with observations of previous Leonid events have demonstrated that it is possible to accurately predict whether or not the Earth will pass through a young dust particle filament of Comet Tempel-Tuttle.
The calculations for 1999 indicate that the Earth will pass through a dust filament of one hundred years old, released by the Comet three revolutions ago. This is expected to occur around 2 a.m. Greenwich Mean Time on November 18, i.e., from most of Europe, the Mediterranean area and northern and west-central Africa during the second half of the night of November 17 to 18! Unfortunately, the Earth will not pass through the core of the filament, but rather through its outer regions. Comparison with similar events in the past results in an expected activity of around 500 or 1000 meteors per hour around the abovementioned time, but these numbers are only indicative: the real frequency may be both higher or lower! However, even if the storm would fail to materialize, a frequency of 50 to 100 meteors per hour is guaranteed.
A recurrence of a fireball storm the night before is highly unlikely.
- WHERE AND WHEN TO LOOK
As explained above, a Leonid meteor storm this year, if it materializes, will only be visible from most of Europe, the Mediterranean area, and northern and west-central Africa. In this part of the world, 2 a.m. Greenwich Mean Time corresponds to 2 a.m.-4 a.m. local time. To see any activity, people there must either stay up long on November 17 or raise early on November 18. At least 50 to 100 meteors per hour will be visible; if a storm materializes, meteor counts can go up to 1000 or more per hour.
However, much is going to depend on the weather that is unstable over all Europe and the Mediterranean area in that time of year. The deserts in the Middle East (Israel, Jordan, ...) may be a good choice, except if the peak occurs significantly later than expected. In western Europe, the French Provence and Southern Spain are among the best places. In Africa, the probability of clear skies increases dramatically the more you move away from Mediterranean influences, and the more you move toward Saharan influences. The Canary Islands also offer good perspectives, provided you climb to altitudes which are above the clouds and provided the peak does not occur significantly earlier than expected. Climate-wise, most of Mediterranean coast, including the North-African part, is to be avoided.
However, climate is only what you expect, and weather is what you get! Therefore, the best strategy to avoid bad weather is closely following the weather charts and travel one day in advance to the location within your "action radius" that offers the most favorable prospects.
Whether you choose to travel or stay at home, you will have to wait and see until the last moment if weather conditions will be favorable - a patch of clouds or a clearing at the right time can create a world of difference!
Besides weather, light pollution is an important factor in choosing an observing sight. Despite last year's fireball storm, most Leonids are not that bright. The more light pollution, the fewer meteors you will see! So, choose a dark spot!
As explained above, Leonid meteors cannot be seen before midnight. Hence, there is no point in starting an observation earlier. However, die-hards who do not want to miss anything of the show should then continue to watch until dawn. People who cannot afford to stay up that long should focus on the period between 1:30 a.m. and 3 a.m. Greenwich Mean Time.
- HOW TO WATCH?
Mind that it can be very cold in mid-November: warm clothing adapted to the local climate is essential!
Since you can never tell in advance at what precise time at which direction in the sky a meteor will appear, you should never fix a particular star, but rather patiently watch a wide area of sky in a relaxed way until a meteor appears. It is not necessary to look in the direction of the constellation of Leo: you will see meteors all over the sky, in all directions.
For comfortable observing, use a reclining chair, and install yourself in a suitable sleeping bag or under several blankets.
- LEONIDS AFTER 1999
Leonid meteor storms may occur in 2000, 2001, and 2002 as well. According to the most recent predictions, a Leonid storm of roughly the same strength as expected this year may be visible from roughly the same area of the world in the morning hours of November 18. The best prospect for the 1998-2002 Leonid "window" are for 2001, however. That year, a Leonid meteor storm in the order of magnitude of ten thousand meteors per hour may materialize over Australia, Japan, the western Pacific and eastern Asia. A similar event will occur over North America in 2002; unfortunately, this event will be partially spoiled by the light pollution of a Full Moon.
GLOSSARY AND ADDITIONAL EXPLANATIONS
COMETS - Comets are small celestial bodies (with a diameter varying from a few kilometers to at most a few tens of kilometers) that revolve around the Sun in long elliptical orbits. Comets consist mainly of ice and dust. When a comet approaches the Sun, part of the ice will evaporate and, because of the resulting pressure, the gas will find its way through cracks and fissures in the thin comet crest and be ejected under the form of "geysers." The evaporated ice of these geysers will feed the coma and the tail of the comet. Together with the evaporated ice, a lost of dust is released. This dust eventually spreads along the entire orbit of the comet, but remains densest in its immediate vicinity. Meteoroid streams (4) usually consist of cometary dust.
METEORS - Dust particles orbiting the Sun and capable of "colliding" with the Earth are called meteoroids. Such a meteoroid has usually the size of a sand grain or a tiny stone. When it enters the atmosphere, with typical velocities of a few tens of kilometers per second - several then thousands of kilometers per hour! - not only the meteoroid but the surrounding air experience enormous friction. This friction causes the air surrounding the meteoroid to give light, in much the same way as an electric current causes the gas in a TL lamp to give light. Meteors typically light up at heights of 90 to 110 kilometers. The resulting light is called a meteor or a shooting star. Usually, the enormous friction causes a meteoroid to disintegrate into the molecules it is composed of: the meteoroid "evaporates" completely. Only the larger and stronger meteoroids may survive traversing the atmosphere. The remainder of the meteoroid that impacts on the Earth is called a meteorite. Leonids are too fragile to produce meteorites, even if they are meter-sized.
Occasionally, meteors are exceptionally bright, brighter that the brightest planets, and sometimes even brighter than to Moon. These meteors are called fireballs.
METEOROID STREAMS AND METEOR SHOWERS - The collection of particles released by a comet (or comet-like asteroid) is called a meteoroid stream. The meteor display in the sky caused by a meteoroid stream is referred to as a meteor shower, or, in case of extremely high activity, a meteor storm.
Meteoroid streams and their associated meteor showers are named either after the comet from the particles originate, or, as is the case for the Leonids, after the constellation in which its radiant (4) is located.
The Leonids are not the only meteor shower we can see. In fact, their are dozens of other meteor showers, but most of them never produce more than a few meteors per hour. Two notable exceptions are the Perseids, active around August 12, and the Geminids, active around December 14. Every year, both showers produce several tens of meteors per hour at their respective peak times.
Finally, we must mention that the Solar System contains a lot of dust particles that do not belong to any particular meteoroid stream. These particles cause so-called sporadic meteors, which may appear any time.
RADIANT - Meteoroids of the same stream (3) orbit the Sun along a common orbit (roughly the orbit of the comet from which they originate). When the Earth crosses a meteoroid stream, our planet is "hit" by a "bombardment" of dust particles which all come from the same direction. The perspective, however, leaves us the impression that the meteor trajectories in the sky, when prolongated backward, originate from a single point, just like the tracks of a long, straight railroad. This point is called the radiant of the meteor shower. Most meteor streams and showers are named after the constellation in which this radiant is located. Even though the backward prolongations of all meteors of the same shower intersect the radiant, the meteors themselves can appear anywhere in the sky. Hence, there is no need to look in the direction of the radiant to observe a meteor shower.
To understand better what happens during a meteor shower, picture the stream orbit as a "race track" along which all meteoroids race at the same speed. Picture the Earth, with yourself as an observer on the Earth, as an "unexpected" obstacle on this race track with which meteoroids may collide, producing meteors in the process. If you look in the direction of the radiant, you will only see short meteors, caused by meteoroids colliding with the Earth's atmosphere while "running" almost straight toward you. If you look at 90 degrees from the radiant, you will see long meteors, caused by meteoroids colliding with the Earth's atmosphere just when they were about to overtake you. If you watch even further away from the radiant, you will again see shorter meteors, caused by meteoroids colliding with the Earth's atmosphere after they had passed you, and thus moving away from you.
More information on the Leonids can be found in the International Meteor Organization's bimonthly journal WGN and on the internet, at http://www.imo.net.
For questions, contact Marc Gyssens at wgn@imo.net or +32-477-64 05 48.
Notice that the International Meteor Organization will send out a new release with first results on the Leonids during the European early morning hours of November 18, immediately after the event. All recipients of the present note will automatically receive the new release.
Hints for visual 1999 Leonid observations by Rainer Arlt
- INTRODUCTION
Summarizing the predictions in short, we expect a strong, narrow outburst of Leonids in November 1999. Since the behavior of the 1998 Leonids and that of many previous years and epochs can be reconstructed with particle models in impressive agreement with the observations, the prediction following from the same models are thought to be quite accurate, too (see, e.g., [1,2] for such models). According to [3], a to-the-minute prediction is possible for November 18, 2h08m Greenwich Mean Time. This is the time of passing the closest dust trail which was ejected by the parent Comet 55P/Tempel-Tuttle in 1899. Meteoroids from other epochs will add to this picture, but strongest activity is expected for this time with no larger deviation than one hour according to the fully independent study in [2]. The maximum ZHR is supposed to be of the order of 1000, but half or twice this value is easily possible, since the prediction of rates is most difficult. Maximum visible rates under a magnitude +6.5 sky will range from almost 15 meteors per minute as seen from the Near East to about 5 meteors per minute on the Canary Islands where the radiant is significantly lower.
- THE OBSERVATION
In case of very high rates, you will run into problems of noting shower and magnitude information for each meteor. First, drop the shower information from your log. The contamination by sporadic meteors will be negligible, whereas the magnitude information is most essential for understanding the Leonid meteoroid stream. Try to report magnitudes for each meteor as long as possible. Your notes, whether on tape or on paper, will just be a sequence of numbers - the magnitudes - plus regular time marks (see below).
As it is highly probable that the main activity will be caused by particles recently ejected from the comet (1899 is only three revolutions ago), we expect a lot of faint meteors in the shower. An abundance of meteors might reduce the attention of the observer to the nicely bright meteors (which will be numerous, even though the population index may be high). Please keep up your vigilance even if the show suggests you to just "sit back."
Limiting magnitude estimates will be difficult during an outburst. At least, you should obtain a limiting magnitude estimate shortly before and a limiting magnitude shortly after the outburst. If the conditions change during extraordinary activity, you may note relative measures like "Lm reduces by 0.1" simply according to your impression. Another possibility is a short break in your observation for limiting magnitude determination. This is certainly the more accurate way, though we will lose a minute or two in recording meteors, which is not considered to be a dramatic loss.
- THE OBSERVING REPORT
If a strong Leonid outburst materializes, we will experience very quick changes in the visible rate of meteors. The information of the activity profile should not be smeared out by choosing observing periods that are too long. Be sure to have enough time marks in your notes. If the rate reaches 3 meteors a minute or more, you can talk on your tape-recorder in real time, that is, without stopping the device. You are then free to make observing periods of down to a minute duration after your observation. Since the recording and replay speed may not be exactly the same, you should speak a few time marks (say every 10 minutes) onto your tape for calibration.
A perfect observing report will list short periods with less than 10~meteors each. If the ZHR goes beyond 1000, it might be possible that you will report periods shorter than a minute. In a similar way, magnitude distributions should contain about 20 meteors, seen in a period of possibly as short as two minutes (if you manage to speak magnitudes for all meteors on the tape). Remember that your individual count for such short periods may not look significant, but the combination of many of these periods reported by many observers at the same time, will yield precise values for the shower's population index and activity in high temporal resolution.
Please, do not forget to give the main direction of your field of view, which is necessary to reduce meteor numbers to actual spatial number densities of meteoroids in the stream, or to flux densities. Field centers should not be chosen below 50 degrees elevation.
Remember that the cloud cover factor refers to the field of view only, not to the entire sky, since we wish to correct only the individual observer's rate, not that of the entire sky. The typical field of view in which 98 percent of the meteors are seen has a diameter of roughly 100 degrees. If clouds appear behind you or near the horizon, not affecting your field, you should not give an obstruction correction in the observing report.
We will be grateful if you send your reports to the IMO Visual Commission, c/o Rainer Arlt, Friedenstrasse 5, D-14109 Berlin, Germany, or by electronic mail to arlt@compuserve.com (avoiding possible system overload at the IMO server).
REFERENCES
- D. Asher, M.E. Bailey, V.V. Emel'yanenko, "Resonant meteoroids from Comet Tempel-Tuttle in 1333: the cause of the unexpected Leonid outburst in 1998," Mon. Not. R. Astr. Soc. 304, 1999, pp. L53-L56.
- P. Brown, Ph.D.~Thesis, Univ. of Western Ontario, London, 1999.
- R. McNaught, D. Asher, "Leonid Dust Trails and Meteor Storms", WGN 27:2, April 1999, pp. 85-102.
More information on the Leonids can be found in the International Meteor Organization's bimonthly journal WGN and on the internet, at http://www.imo.net.
The above article was taken from WGN 27:5, October 1999, pp. 235-236.
For questions, contact Marc Gyssens at wgn@imo.net or +32-477-64 05 48.
Notice that the International Meteor Organization will send out a new release with first results on the Leonids during the European early morning hours of November 18, immediately after the event. All recipients of the present article will automatically receive the new release.
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This page was last modified on November 10, 1999 by Casper ter Kuile, Carl Johannink, Hans Betlem |