• Daniel Fischer: Report from the Jordanian Leonids observing camp at Al Azraq
  • 2650 KB Animated Gif of an exploding Leonid meteor and its morphing train
  • Arne Danielsen: Pictures of the 1999 Leonids meteor shower
  • ESO: Leonids 1999, first reports on this event
  • ESOC's Leonids count
  • Leonids 1999: ASTRONET's links and background information

    From: Joan and David Dunham
    Subject: AstroAlert: Two more confirmed lunar impacts - now 5

    David Palmer reports two more lunar impacts that he videorecorded at his home in Greenbelt, Maryland at 3:49:41 and 4:08:00 UT of 1999 November 18. The times are estimated to be accurate to +/-3 seconds since they were obtained just by calibrating the VCR clock with time from the CNN cable TV broadcast. The flashes are also in the video recording that I made at Mount Airy, about 60 km to the northwest, bringing the total now to five confirmed lunar impacts, four of them on my tape and also on other videotapes made by others, and the other, the first one reported, confirmed with Brian Cudnik's timed visual observation.

    Brian Cudnik reports that the flash he saw was yellowish-orange in color, redder than nearby psi1 Aquarii. All of the videorecordings are black-and-white. A third probable untimed visual confirmation of that event has been provided by Steve Hendrix, who watched the dark side of the Moon with a 4.5-inch Meade telescope from Cameron, Missouri from 4:40 to about 4:55 UT. It was the only flash that he saw during that period and it matched Brian Cudnik's description. Before hearing about Cudnik's and my description of the flash, Hendrix was hesitant to share his observation since he had "never seen anything like this before and didn't want to appear over zealous".

    A summary of the five confirmed lunar impacts are given in the table below. This is an ASCII plain text table that must be viewed with a fixed-space font such as Courier for the columns to line up properly. For the time being, we are naming these with letters in the order of discovery. The UT date is 1999 November 18. In each case, the events were confirmed on my videotape made at George Varros' backyard in Mount Airy, Maryland, and the timings are from my tape.

               Accuracy, Approx.  Discovered  Selenographic
    Name  U.T.    sec. Mag1  Mag2    by       Long. Lat. Description
       h  m   s
    D  3:49:40.5   0.4   3    7  David Palmer  48W   1N 175km SW of Kepler
    E  4:08:04.1   0.6   5    8  David Palmer  70W  15S 175km S of Grimaldi
    A  4:46:15.2   0.1   3    8  Brian Cudnik  71W  14N  50km ENE of Cardanus
    B  5:14:12.93  0.05  7    8  Pedro Sada    58W  15N 200km WNW of Marius
    C  5:15:20.23  0.05  4    7  Pedro Sada    59W  21N  75km S Schiaparelli

    Mag1 is the approximate magnitude of the flash estimated from my tape on the half-frame on which it first appears. Mag2 is the estimated magnitude a half-frame, or 1/60th second, later. In all cases except D I can't see any evidence of the flash in the half-frame 1/30th second after the first one, except for D, where it seems to appear there at about 9th mag. The selenographic locations for D and E are very approximate, based on rough estimates rather than measurements, and could be in error by 5 deg. or more. The others should be accurate to within about 2 deg. or 50 km. All of these are in the western part of Oceanus Procellarum (Ocean of Storms) except E, which is in highlands area a short distance west of the western shore of Oceanus Procellarum. The times of B and C have been determined by Don Stockbauer, Victoria, Texas, after creating an accurately time-inserted copy using an IOTA- Manly video time inserter. He also determined the time of A, but for technical reasons to less accuracy; it will be possible to refine it later. D and E have been timed from the tape just using a stopwatch.

    Several have asked me how large the impacting meteors are, and if the new crater they form might be seen. I need help from an expert in impact dynamics on this - I don't have expertise in that field. I have heard one estimate that the impactors, to produce flashes this bright, are meter- size, but another estimate is that they may be just 100 grams or so. In any case, I believe that the "splash" that these objects made are less than 100m across and will not be visible with Earth-based telescopes. In 2003, the Japanese Selene spacecraft plans to map the Moon from low orbit in detail, and coparison of its images with those of Lunar Orbiter, Apollo, and/or Clementine will hopefully reveal some small new craters.

    Ray Sterner and I digitized our images of B and C yesterday and we hoped to get them posted on our Web site at http://iota.jhuapl.edu, but that might not be possible now until Monday. In the meantime, we will post the latest information about these flashes at the main IOTA site including Sada's images of B and C, and Palmer's images of D and E. I don't plan to make any more mass-mailings like this one about these events, but will distribute future updates to a few who are especially interested. Otherwise, check the Web site for further updates, but I will try to answer specific questions about these events.

    David Dunham, IOTA, 1999 November 24

    PS - After sending this, I will not be at this address, but will be reachable at david.dunham@jhuapl.edu, phone 1-240-228-5609.

    Joan and David Dunham
    7006 Megan Lane
    Greenbelt, MD 20770
    (301) 474-4722

    Forwarded From David Dunham

    Two more lunar impacts CONFIRMED, on 2 videos

    Pedro Valdés Sada reports two lunar flashes that he videorecorded near Monterey, Mexico, about half an hour after the event seen by Brian Cudnik and recorded by me that is now so famous. He gives the times in his message, copied below. They are also on my tape, made in Mount Airy, Maryland, at the times he gives! Later today, we will digitize these two new flashes and put them up at http://iota.jhuapl.edu

    They are also near the lunar equator. We will be determining the exact times from the tapes when we can; I'm sure they will agree to within the 1/15th or so second of timing that we can probably recover from the tapes. I had a WWV minute tone recorded at 5:07:00 UT, 7 and 8 minutes before the flashes, respectively. The new objects are also probably Leonids, since it was still near the time the peak was striking the Moon, but of course we do not know for sure, since we don't know from which direction the meteoroids approached the Moon.

    For observers, a key to my success in this endeavor was the focal reducing lens that I purchased from Orion; it decreased the f-ratio of my 5-inch Schmidt-Cassegrain telescope from 10 to 6.3. That not only increases the field of view by more than a factor of 3 in area, but also increased sensitivity by concentrating the seeing disk of point sources onto fewer pixels, and allowed, for example, recording (faintly) the Earthlit dark side of the Moon.

    By measuring images showing the lunar cusps and terminator taken before and after the 4:46:15 UT event, I was able to determine that it occurred at an angle (measured from the Moon's center, called "cusp angle" in occultation terminology) of 77 deg. from the north cusp. Using also=20 the distance of 1.7' in from the edge, this puts the impact point in Oceanus Procellarum (Ocean of Storms) about 50 km east-northeast of the center of the 50-km crater Cardanus, at selenographic longitude 71 deg. W., latitude 14 deg. N., with estimated accuracy of 2 deg. or 50 km.

    David Dunham, IOTA, 1999 November 23

    Date: Tue, 23 Nov 1999 03:00:33 -0600
    From: Pedro Valdés Sada 
    To: Joan and David Dunham 
    CC: David Dunham 
    Subject: Re: Lunar impact seen & videorecorded; more records sought

    Hi David,

    I videotaped the non-illuminated side of the Moon for a while before the leonid meteor radiant rose. There was some trouble while doing it because I had allready committed myself to help with a large number of people that attended a talk I gave that night on the subject and then stayed for the meteor shower. So I had to keep an eye on the camera and telescope at the same time I was answering questions and talking with people.

    I checked my tape for the 4:46:15 UTC meteor crash on the Moon and could not find it. I must have been aiming elsewhere. I am not sure where because the FOV was too bright from the glare and I could not see the limb. Another problem was that the portable telescope was not polar alligned very well and I had to keep adjusting it every 5-10 minutes so the Moon would not drift out of the FOV.

    At any rate, I have not checked all the tape, but managed to identify= two very suspicious-looking flashes that lasted at most 2-3 frames. They= occurred at 5:14:13 and 5:15:20 UTC (+-1 second). Please check your tape and pass it along to see if anyone else can confirm them. The second one in particular, was right on the edge of my camera's FOV. The first one I am pretty sure was real since the image was a bit out of focus and looked very much like the stars I taped for calibration after the Moon set (the focus must have drifted since it was OK at the start of the night). I will try and digitize the two frames involved. Unfortunately, on my VCR I can only freeze-frame the second fainter one. There seems to be a brighter one in between frames that I cannot freeze on the screen but can see momentarily. As for location on the Moon of the possible impacts I cannot say for sure since the Moon drifted constantly. I can say that it was near the equator and close to the terminator since it drifted into the FOV after a couple of minutes.

    Sorry that I cannot be more precise on the location and magnitudes. I will try to grab the images involved and at least get a rough estimate of the magnitude.


    Pedro Valdés Sada
    Univ. de Monterrey, México

    From: Joan and David Dunham

    21 Nov 1999

    Lunar impact seen & videorecorded; more records sought

    Brian Cudnik, Houston, Texas, saw a brief flash near the center of the Moon's dark side near the edge at about 4h 46m 20s U.T. November 18. Observing with a 36cm telescope, he estimated that the flash, taking a fraction of a second, was at least as bright as nearby 4th-mag. psi1 Aqr. He is sure of the event, but asked me for confirmation, to see if a satellite glint or other close-to-Earth phenomenon might have been involved. The observation was confirmed in a video recording that I made using a 13cm telescope at George Varros' home in Mount Airy, Maryland, with relatively dark skies about 35 miles northwest of Washington, DC. The event occurred at a cusp angle of around 75 - 80N (10 to 15 deg. north of the lunar equator) 1.7' from the Moon's edge. The flash, timed from the videotape at 4h 46m 15s, is visible in only two video frames, the first at about 3rd magnitude and the second at about 8th magnitude. The images can be viewed at http://iota.jhuapl.edu. The object was probably a Leonid since the peak of this year's display was at 2h UT as seen from the Earth. The trailing Moon would arrive at the same solar longitude about 3h later, near the time of the observed impact. I also recorded 5 lunar occultations of 8th-magnitude stars an hour before the impact, and also have an image of psi1 Aqr on the tape. Analysis of those images and of the impact images will permit a reasonably good determination of the brightness and location of the impact flash. Anyone else who was recording the dark side of the Moon at the above time should check their data and report their results to me, preferably at both dunham@erols.com and david.dunham@jhuapl.edu. I am interested in knowing about ALL observations of the lunar dark side made between 4:00 and 6:00 UT November 18th when the Moon should have been struck by the brunt of the Leonid storm. There are other fainter flashes in my video record, but some of them are spurious video artifacts. I looked at one, and it did not have the strong stellar appearance of the 4:46:15 flash. But before checking very much for other events, I want to know if there are any other observations that might confirm them. Unfortunately, I'm affraid that most observers in the central and western USA, where the Moon was best placed at the time, bypassed the evening lunar observations in favor of seeing the Leonid meteors during the early morning hours; I have heard of only a few lunar attempts. At my location, fortunately conditions were excellant with the Moon 15 deg. above the horizon at 4:46 UT. I was able to continue the observations until 5:30 UT.

    I believe this is the first confirmed lunar impact observation. A probable lunar meteor impact was photographed on 1953 November 15 by Dr. Leon Stuart; see http://www.spirit.net.au/~minnah/LunarFlare.html.

    David Dunham, IOTA, 1999 Nov 21

    Joan and David Dunham
    7006 Megan Lane
    Greenbelt, MD 20770
    (301) 474-4722

    NASA Space Science News for November 21, 1999

    Meteor Balloon Update: Replays from the 1999 NASA meteor balloon flight are now available at LeonidsLive.com. The peak of the Leonid meteor storm did not take place over the eastern US where the balloon was launched. Nevertheless, some interesting sights and sounds were recorded. Also featured on the LeonidsLive.com website is a spectacular picture of a Leonid fireball exploding over the Italian Alps on November 18, 1999.

    Leonids, Live!

    Associated Press


    November 19, 1999

    Brilliant Leonid storm likely fodder for later Lincoln speech

    SAN MARCOS -- The Great Emancipator was no Chicken Little.

    Southwest Texas State University astronomer Don Olson believes he has proof that Abraham Lincoln saw the brilliant Leonid meteor storm of 1833 when Lincoln was a young man living in New Salem, Ill.

    The future 16th president likely was one of the few people around who didn't think the sky was falling, Olson said.

    Full story here.

    I N T E R N A T I O N A L M E T E O R O R G A N I Z A T I O N

    From Marc Gyssens


    Experienced visual observers watching near Malaga and at the Sierra Nevada Observatory in Spain and near the Gorges du Verdon in the French Provence report that Leonid meteor activity peaked at up to 30 meteors per minute shortly after 2 am Greenwich Mean Time. This activity was characterized by a lot of faint meteors and almost no fireballs.

    Meteor astronomers reduce the actual numbers of meteors seen to a standard value, called the Zenithal Hourly Rate (ZHR), which takes into account the quality of the sky as well as the direction from which meteoroids enter the atmosphere. The peak activity reported by the abovementioned groups of observers corresponds with a ZHR around 5000, which is considerably more than what most meteor observers had hoped for (around 1000).

    Preliminary reports of other observing groups at Tenerife, Canary Islands, near Valencia in Spain, and in Jordan confirm the picture sketched above.

    Radio observations from Japan and the Czech Republic also indicate a peak time between 2:00 and 2:10 am Greenwich Mean Time.

    The observed peak time coincides almost perfectly with the peak time of 2:08 am Greenwich Mean Time predicted by Asher and McNaught, indicating that the activity was due to the dust trail created the Leonids' parent comet, Tempel-Tuttle, about 100 years ago (i.e., 3 revolutions ago of the Comet around the Sun).

    Marc Gyssens
    International Meteor Organization

    Below is a more technical description of the observed Leonid peak activity.

           I M O   S h o w e r   C i r c u l a r

    LEONID Activity 1999

    Visual observations of the 1999 Leonids revealed a distinctive peak with a ZHR of about 5000 on November 18, 2h05m +/-10m UT (solar longitude 235.287 +/- 0.007, eq. 2000.0). ZHR levels were above 1000 from roughly 1h30m UT to 3h00m UT corresponding to 235.26 to 235.32 degrees in solar longitude.

    All observers who were able to view the peak under good sky conditions reported an abundance of faint meteors and a relative absence of fireballs. Some observers noticed a drop in the population index (i.e., a larger fraction of brighter meteors) after the peak.

    Reports from Mohammad Odeh (Jordanian Astronomical Society) and Casper ter Kuile (Dutch Meteor Society, observing near Valencia, Spain) are very consistent with the picture sketched above.

    In addition, radio data from K. Maegawa (Toyokawa Meteor Observatory, Aichi, Japan) reported by Kazuhiro Suzuki and the backscatter radar data from Ondrejov Observatory (Czech Republic) reported by Petr Pridal and Rosta Stork yield a peak time between 2h00m UT and 2h10m UT.

    It seems that the peak time of 2h08m UT predicted by Asher/McNaught is confirmed within a margin of at most a few minutes, although the observed activity is significantly higher. It is reasonable to conclude that the peak activity has been caused by the 3-revolutions old dust trail of 55P/Tempel-Tuttle.

    The following observers have contributed data immediately after the event, from which the ZHR profile given below has been derived:

    Per Aldrich, C.L. Chan, Asdai Diaz, Yuwei Fan, Fei Gao, Lew Gramer, Andre Knoefel, Wen Kou, Alastair McBeath, Tom Roelandts, Sirko Molau, Renke Song, Wanfang Song, Honglin Tao, Dan Xia, Dongyan Zha, Jinghui Zhang, Yan Zhang, Jin Zhu.

    (For groups of observers, only the name of the contributing observer has been mentioned.)

    Date   Period (UT)  ZHR  +-
    Nov 17  0600-1000   16    2
    Nov 17  1600-2010   30    5
    Nov 17  1900-2200   53   14
    Nov 18  0030-0100  130   90
    Nov 18  0100-0115  490  230
    Nov 18  0115-0130  770  160
    Nov 18  0130-0145 1040  660
    Nov 18  0145-0202 4100  840
    Nov 18  0200-0215 5000 1100
    Nov 18  0212-0230 2400  280
    Nov 18  0243-0247 1100  160
    Nov 18  0320-0330  470   70
    Nov 18  0420-0430  180   40

    ZHRs are computed with a population index of 2.0, zenithal exponent of 1.0.

    Marc Gyssens, 1999 November 18, 7h UT.


    18 November 1999


    Preliminary results from observations of last night's Leonid meteor storm indicate that the prediction made by Dr David Asher of Armagh Observatory and Rob McNaught of the Australian National University of a strong shower peaking at around 2.08 a.m. UT (or GMT) were spot on - even to the extent that faint meteors would dominate compared with the exceptional fireball display last year. This is the first time that astronomers have succeeded in making such an accurate prediction of a meteor storm.

    The peak rate of meteors is more difficult to predict than the time of maximum. Asher and McNaught had been cautious with their public statements, but had reason to believe from their latest work that it could be higher than the 20 per minute they had been suggesting. The preliminary observations seem to show that a higher rate did indeed occur.

    'We are delighted with this vindication of the method used by Rob and David', said Professor Mark Bailey, Director of the Armagh Observatory. The only cause for regret in the UK today was that most of the country was blanketed in cloud at the crucial time.

    Attention will now be focussed on their prognostications for the next three years. Next year (2000), they predict, will be 'the calm before the storm': the Earth will pass through the centre of the broad meteoroid stream without passing directly through any of the dense, recently ejected dust trails. 'It's rather like the ten-pin bowler who, having left half a dozen pins standing after the first shot, bowls clean through the gaps with the second shot' said Professor Bailey.

    Next year's observations will, however, be important for gathering further observational information about the location and extent of the dust trails. The Earth will pass, for the first time ever, through the outskirts of the dust trail deposited when Comet Tempel-Tuttle made its appearance in 1866. This trail could prove to be denser than expected.

    The showers in 2001 and 2002 are expecte to be dominated by close encounters of the Earth with this 1866 trail. Predictions based on their present model lead to zenithal hourly rates well in excess of 10,000 meteors per hour. Actual observations in 2000 should help to determine whether this is correct, or an under- or over-estimate.

    NASA Space Science News for November 18, 1999

    Leonids Rain in Spain -- Sky watchers in Europe and the Middle East were treated to a frenzied outburst of Leonid meteors on Thursday morning.

    MORE: The NASA meteor balloon flight captured video of numerous Leonids meteors. Replays and highlights will be available later today at http://LeonidsLive.com.

    NASA Ames Research Center, Moffett Field, CA

    Nov. 18, 1999


    Astrobiologists on a NASA mission to study the Leonid meteors were in the right place at the right time to study a rare natural phenomenon -- a meteor storm.

    At the peak of the storm, which occurred at 02:10 GMT, Nov. 18, the Leonid meteors were falling from the sky at a rate of 2,200 per hour. A meteor shower is classified as a storm when the rate exceeds 1,000 meteors per hour.

    "It's getting to the point where we can't click fast enough to keep up with the meteors!" exclaimed Dave Holman of the California Meteor Society, one of several amateur astronomers on the meteor-counting team. A total of 15,251 meteors were counted during the six-hour observation period on the overnight flight from Israel to the Azores.

    "That's a lot of meteors!" said Chris Crawford, the amateur astronomer responsible for compiling the data collected from each person counting the meteors. "I've seen just about as many meteors in one night as I've seen in over 34 years of meteor watching."

    Near real-time data on the number of meteors falling per hour was provided to NASA and the U.S. Air Force by a team of amateur astronomers who counted the meteors using virtual reality goggles and laptop computers. The meteor counting team was aboard the ARIA, one of two aircraft provided by the United States Air Force to support this mission. The data was sent from the ARIA, an EC-18 aircraft, to the ground via the TDRS satellite system. NASA and the Air Force are joint sponsors of the Leonid Multi-instrument Airborne Campaign.

    "I am ecstatic over how well this night went!" said Peter Jenneskins, chief scientist for the Leonid mission. "Our models proved to be right on for predicting where and when the meteor storm would take place. We gathered some fantastic images, and the data obtained should provide valuable insight into the role meteors may have played in the evolution of life on Earth."

    While viewing the horizon at one point during the storm, meteors, lightning and sprites could be seen from the planes. Sprites are lightning phenomena that rise from the ground to the sky. "For 10 minutes we had a view of the way the sky may have looked on Earth over 4 million years ago," Jenneskins said. "It was an awesome sight."

    The second observing night of the Leonid astrobiology mission began when the ARIA and FISTA aircraft left Tel Aviv at about 23:00 GMT, Nov. 18. The flight crew of the ARIA reported seeing two meteors almost as soon as the wheels left the ground. Once the planes reached altitude, they began flying in 150 nautical mile flying patterns from east to west over Israel and the Mediterranean. These orbits provided a unique opportunity for scientists on the planes and scientists on the ground to collaborate. The data collected from the planes will be combined with visual, radar and radio observation data from Israeli scientists on the ground to form an extremely comprehensive data set regarding the Leonid meteors.

    The aircraft stopped the orbits after one hour and continued westbound towards the Azores, flying approximately 80-100 nautical miles apart at 37,000 feet. ARIA's path flew the scientists off the coast of Crete and over Sicily, while FISTA's path flew over mainland Greece and the boot of Italy. ARIA then flew over the top of Menorca and Majorca, crossed central Spain by Madrid, and continued over the top of Portugal down to the Azores. FISTA flew over Sardinia and Barcelona and out the northwest corner of Spain, and then down to the Azores. The planes landed at Lajes Airbase in the Azores at approximately 07:15 GMT, Nov. 18.

    While over Spain and Portugal, scientists on the aircraft performed coordinated observations with a series of ground based observing teams.

    "The coordinated air and ground observations that were conducted during the flight are an invaluable part of this highly successful mission," stated Col. S. Pete Worden, of the United States Air Force headquarters, Washington, D.C. "Not only do we have a phenomenal set of data from the air, but we also have complimentary data from the ground that can be used to help us better understand and predict meteor storms and the impact they may have on space operations." Col. Worden flew aboard the ARIA aircraft from Tel Aviv to the Azores. The Air Force operates more than 100 satellites that could be affected by a meteor storm.

    It takes the Earth a few days to get through the debris trail left by the periodic comet 55P/Tempel-Tuttle that produces the Leonid meteors. Therefore, one more observation night is scheduled during a flight from the Azores to Patrick Air Force Base in Florida.

    The scientists and crew aboard the ARIA and FISTA are not the only people able to see the Leonid meteors from the unique vantage-point of an airplane. Live video from the plane is being sent to the internet during the mission for people on the ground to watch. For current information about the Leonid Multi-instrument Airborne Campaign visit: http://leonid.arc.nasa.gov.


    Leonids storm peaks at 2,200 meteors per hour over Middle East

    The Leonids erupted early today with a meteor storm that was the most vigorous display of celestial fireworks in 33 years. Airborne astronomers analyzed the shooting stars with an array of instruments mounted in a pair of jets flying together above the clouds and urban smog over the Middle East, where viewing conditions were best.

    Initial estimates pegged the storm's peak at 2,200 meteors per hour at 4:08 a.m. over Israel (9:08 p.m. EST Wednesday), generally living up to all but the most optimistic forecasts.

    While the shower was a rare event, the number of meteors seen was a fraction of those counted during the 1966 Leonids, a meteor hurricane that deluged skies over North America with 144,000 per hour.

    Sixty researchers aboard the $1 million joint NASA-Air Force mission hollered and hugged as the Leonids barrage intensified, and the jets traced slow circular routes over the Mediterranean between North Africa and Cyprus. Individual meteors soon multiplied to a half-dozen white streaks screaming over the horizon at 40 miles per second.

    ''I'm not on Cloud 9 - I'm above it!'' quipped Jane Houston of the California Meteor Society.

    Nicknamed ''shooting stars,'' meteors are generated by tiny particles shed by passing comets. In the case of the Leonids, the debris comes from Comet Tempel-Tuttle as it orbits the Sun every 33 years. Earth plows through the cosmic litter every November 18. Last year's Leonids peaked at 250 meteors per hour.

    ''I've never seen anything like this before, even on video,'' exulted the mission's chief scientist, Peter Jenneskins, of the SETI Institute and NASA's Ames Research Center.

    That Jenneskins and others finally experienced a meteor storm this year is fortunate. Glitches in Earth's orbit, plus the powerful gravitational tug of Jupiter, will cause the comet to veer slightly off course during its next one or two 33-year orbits.

    As a result, astronomers believe the Leonids might be reduced to a drizzle and the celestial fireworks that marked the sunset of the millennium may not explode overhead again in grand style until the end of the next century.

    NASA and the Air Force mounted the science mission using a pair of refurbished jets. They landed at Lajes Air Force Base in the Azores, islands in the North Atlantic, at dawn following the mission.

    The military has a keen interest in meteors because of the potential damage they can cause to 600 orbiting telecommunications and intelligence satellites. The chances are low that an incoming particle the size of a split pea would knock out a satellite with a direct hit. But a cloud of particles could do damage.

    An Air Force spokesman today said no reports of Leonids damage have been received so far. Most government and commercial satellite owners had taken safety precautions, including NASA, which shut down the Hubble Space Telescope and the orbiting observatories.

    Astronomers on the jets were studying the Leonids with a variety of instruments to determine the particles' behavior and physical characteristics.

    Rather than look throughout the aircrafts' tiny porthole windows, the observers rigged video cameras to scan portions of the night sky and observed the storm on monitors.

    23 november 1999

    Beste waarnemers,

    Mijn felicitaties aan alle waarnemers van de diverse expedities naar Spanje, Portugal en La Palma. Zo te lezen in de eerste berichten is de oogst erg groot en het zal nog wel even duren voordat alle waarnemingen zijn uitgewerkt.

    Hierbij een kort verslag van mijn waarnemingen van de Leoniden op La Palma, Canarische eilanden. Het weer op La Palma was helaas niet zoals het behoort te wezen, maar in de nacht van 17/18 november was er gelukkig met radio en oog toch het een en ander te beleven.

    Eerst de waarnemingen met de radio. Met een Yupiteru MVT-9000 scanner met een dipool als antenne werd geluisterd naar forward-reflecties van het videosignaal van een TV zender op 48.242 MHz in Muro, Portugal. Gezien de grote afstand, ongeveer 1580 km, viel me het aantal reflecties van de sporadische meteoren in de week voorafgaand aan de Leoniden niet tegen. Deze "sporadische" activiteit varieerde van 30 refl/h om 18h tot 200 refl/h om 6h UTC. Op 17/18 november steeg rond 2h UTC het aantal reflecties tot een maximum van 400 refl/h , ongeveer het drievoudige van de gemiddelde sporadische activiteit. Erg opvallend waren de grote dopplershift en grote signaalsterkte van vrijwel alle reflecties tussen 1h52m en 2h10m UTC. Deze head-reflecties komen onder normale omstandigheden slechts enkele malen per uur voor, maar om 2h01m telde ik er 10 per minuut. De grote dopplershift kan verklaard worden door de grote snelheid van de Leoniden (71 km/s) en door het feit dat radiant en TV zender vanuit mijn locatie in dezelfde richting lagen. Het effect was als bij een vuurwerk met veel luchthuilers! Het aantal langdurige reflecties was veel lager dan bij het vuurbollenspektakel van 16/17 november 1998. Toen werd gedurende een aantal uren de ionosfeer dermate bestookt, dat er vrijwel continu reflecties plaats vonden. Een meer gedetailleerd verslag over de radiowaarnemingen komt later als de waarnemingen zijn uitgewerkt.

    Tijdens de radiowaarnemingen, begonnen om 0h18m, was het volledig bewolkt, met regenbuien en een harde wind. Het horen van een grote Leonidenactiviteit op de radio en niets kunnen zien was bepaald erg frusterend. Het aantal reflecties was tegen 3h UTC al flink gedaald, de opvallende luchthuilers waren gereduceerd tot 1 per minuut. Pas om 3h30m begon de bewolking te breken en kon ik mijn visuele waarnemingen om 3h36m beginnen. Bij een Lm = 5.5 zag ik ruim 100 meteoren per uur. Tegen de ochtendschemering was dit gedaald tot 30 meteoren per uur. Hieronder een samenvatting van mijn visuele waarnemingen. Hierbij moet wel worden aangetekend dat ik een vrij onervaren waarnemer van visuele meteoren ben. Wie weet heb ik de smaak te pakken gekregen?

    Met vriendelijke groeten, Ton Schoenmaker, PA0EFA

    observer: Ton Schoenmaker
    date:     17/18 November 1999
    location: San Nicolas, La Palma, Canary Islands
              28.59 North, 17.87 West
    observations near zenith
          UTC        Teff    Lm   Leo   spo
    03h36m - 04h01m  0.32    5.5   35    1
    magn.    -1   0   +1   +2   +3   +4
    Leo       1   11   9    9    4    1
    spo                     1
          UTC        Teff    Lm   Leo   spo
    04h07m - 04h39m  0.40    5.5   24    0
    magn.    -4   -2   -1   0   +1   +2   +3   +4
    Leo       1    1    1   5    7    4    4    1
          UTC        Teff    Lm   Leo   spo
    04h57m - 05h28m  0.46    5.5   20    2
    magn.    -2   -1   0   +1   +2   +3
    Leo       1    1   6    2    7    3
    spo                          2
          UTC        Teff    Lm   Leo   spo
    06h18m - 06h33m  0.23    5.5    7    2
    magn.     0   +1   +2   +3   +4
    Leo       2    1    2    2
    spo                      1    1

    Astronomische Persberichtendienst

    Utrecht, 18 november 1999


    Een groep amateurastronomen van de Volkssterrenwacht Sonnenborgh uit Utrecht is in de nacht van 17 op 18 november getuige geweest van een regen van "vallende sterren", afkomstig van de Leonidenzwerm. Tijdens het hoogtepunt waren er ongeveer 20 tot 30 meteoren per minuut te zien. Gedurende een tijdspanne van ca. 15 minuten, dat keurig samenviel met het voorspelde maximum, verschenen er er honderden meteoren.

    De Leonidenzwerm is een wolk stofdeeltjes, afkomstig van de komeet Tempel-Tuttle, waar de aarde jaarlijks doorheen trekt. Tijdens hun val naar de aarde veroorzaken ze een lichtstreep aan de hemel, die afkomstig lijkt te zijn uit het sterrenbeeld Leeuw, vandaar de naam Leoniden. De aantallen Leoniden zijn de laatste jaren flink opgelopen, doordat komeet Tempel-Tuttle vrij onlangs (februari 1998) voor het eerst in 33 jaar weer dicht bij de aarde kwam. Vorig jaar was ook een verhoogde activiteit voorspeld in de nacht van 17 op 18 november, maar de omstandigheden om dit kortdurende verschijnsel te zien waren toen voor ons land niet optimaal. Wel werden we verrast door veel heldere meteoren in de nacht van 16 op 17 november, wat de indruk wekte dat de astronomen een rekenfout hadden gemaakt. Echter, ook op het voorspelde tijdstip werden er in Azie veel meteoren gezien, maar een echte regen bleef uit.

    Dit jaar waren de verwachte omstandigheden juist goed voor Europa: op het moment van het voorspelde maximum, rond 3 uur 's nachts, stond het sterrenbeeld Leeuw al vrij hoog aan de hemel, terwijl de maan al onder was en niet meer stoorde. Maar gezien de te hoog gespannen verwachtingen in 1998, bleef iedereen er dit jaar wat nuchterder onder. Toch waren in het hele land waarnemers paraat om getuige te zijn van het mogelijke spektakel. Helaas gooide het weer roet in het eten. Bewolking, regen en natte sneeuw verhinderden vrijwel overal het zicht op de sterrenhemel. Maar tussen de buien door waren er opklaringen.

    Ondanks het slechte weer besloten de Utrechtse waarnemers om toch naar de Ginkelse hei bij Ede te gaan, waar men minder last heeft van storend stadslicht. Tussen 24 uur en 2 uur komen daar enkele opklaringen voorbij, maar worden er niet echt veel meteoren gezien. Een flinke sneeuwbui dwingt de waarnemers om in de auto's te schuilen. Maar rond 2.50 uur breekt er een gaatje in de bewolking en worden er in korte tijd enkele meteoren gezien aan dit kleine stukje van de hemel. Als iets voor drie uur ook het sterrenbeeld Leeuw zichtbaar wordt en het verder opklaart, schieten de meteoren overal langs de hemel. Iedere paar seconden zijn er meteoren te zien, maar ook zijn er momenten waarop er binnen een tot twee seconden wel vier of vijf zichtbaar zijn. De helderheden van de meteoren liggen voornamelijk tussen magnitude 2 en -1. Zwakkere meteoren worden weinig gezien. De helderste exemplaren waren van magnitude -4 tot -5, maar van een vuurbolregen was geen sprake.
    Tussen 3 en 3.15 uur zijn er naar schatting enkele honderden meteoren zichtbaar geweest. Bij een echt wolkenvrije hemel zouden vermoedelijk ook veel zwakkere meteoren zichtbaar geweest en was dit getal nog veel hoger geweest. Na 3.15 uur trok de hemel weer snel dicht en waren er door kleine gaten nog maar enkele meteoren te zien. Het leek alsof de activiteit weer snel afnam.
    "Geen sterrenregen zoals in 1966, maar wel een weergaloze show van meteoren", aldus Robert Wielinga van de Volkssterrenwacht Sonnenborgh.

    Het bureau van Stichting "De Koepel" in Utrecht heeft inmiddels contact gehad met verschillende amateurastronomen in Nederland, maar die hebben door het slechte weer weinig kunnen zien. Het lijkt erop alsof de Sonnenborgh-groep zeer veel geluk heeft gehad.

    Waarnemers van de Dutch Meteor Society en de NVWS Werkgroep Meteoren zijn op voorhand het slechte Nederlandse weer ontvlucht en zijn naar verschillende plekken in Zuid-Europa getrokken. Via e-mail zijn van hen de eerste enthousiaste waarneemverslagen binnengekomen. Ook zij hebben rond 3 uur gedurende korte tijd zeer veel meteoren gezien. Andere waarnemers in Europa melden soortgelijke ervaringen.

    Leonids in Portugal - 2500 in 2:30 hours !

    Date: Thu, 18 Nov 1999 03:54:22 +0000


    I have just arrived from watching the Leonids. It was a clear nigth with a clear 6 mag. limit to the naked eye. The shower startedd about 00:20 (GMT) and for the next 3 hours me and a dozen of friends started to count them until they were just too much for us to count. The shower begun with the rate of 100/hour and reached the peak about 02:00 with a rate of more than 1000/hour. We extimated 2500 in two and a half hour.

    It was breathtaking!

    Paulo Almeida
    LX200 10" @ 39º52'11"N-8º55'47"W

    Leonids, Portugal - Peak was visible!

    Hi everyone!

    Here, Leonids peaked between 1:45UT and 2:30 UT. It was an amazing show, max rate around 600 / 700 meteors per hour! (limiting magnitude arround 5.3)

    After the peak, the number of meteors decreased a lot, arround 70 meteors per hour at 4:00UT (but I didn't count them carefully)

    I saw first leonid arround 0:20UT. So, don't give up too early!

    There weren't any fireballs but most meteors left beautifull brief trails.

    Good Luck! Clear skies!

    Pedro Miranda

    From: Casper ter Kuile

    Happy and thank you!

    Hi everybody,

    Team "Delingha"of the Dutch Meteor Society reports from location Valencia / Alicante - Spain

    The show is over now. And it has been a extraordinairy fine show. Higher rates than hoped for.

    Time of highest activity is almost equal as expected by Asher / McNaught.

    All impressions are of my own. Details reports of our experienced observers will follow soon. So please stay tuned with DMS!

    Our website will be updated soon.

    Many, many thank go to our worldfamous meteorologist Jacob Kuiper who guided us to a fine clear spot in Spain without clouds.

    We will keep you informed.

    Very best wishes to all of you.

    From: Casper ter Kuile

    Thu, 18 Nov 1999 03:55:26 +0100

    Raining Leonids !!!!!


    They did it!

    Team "Delingha"of the Dutch Meteor Society located between Valencia and Alicante in Spain reports....

    We observed many, many, many Leonids falling from the sky! Our experienced visual observers counted about 30 Leonids per minute! Remind this is a very first and rough estimate!

    The time of the maximum is somewhere between 2 and 2:30 UT approximately.

    More detailed reports later.....


    Hi to All!

    Team "Delingha"of the Dutch Meteor Society reports...

    Location Valencia / Alicante - Spain.

    Time: 01:25 UT

    Rates are sharply increasing now!!!

    About 15 minutes ago our visual observers reported about 5 Leonids per minute!

    Keep you informed!


    From: Casper ter Kuile
    Subject: Leoniden report 1

    Hi to all,

    Team "Delingha" of the Dutch Meteor Society is now situated between Valencia and Alicante at the east coast of Spain.

    We are obsereving with 11 observers at two locations and lots of photographic equipment. See out website for details.

    It is now 01:00 UT and rates finally are rising!

    We will keep you informed!

    Clear slies to you all!


    NASA Ames Research Center, Moffett Field, CA

    Nov. 17, 1999


    Astrobiologists began their first airborne observation night to study the Leonid meteors on Nov. 16, as the Earth began to enter the debris train left by the periodic comet 55P/Tempel-Tuttle.

    At 21:50 GMT, on Nov. 16, the ARIA and FISTA, two United States Air Force planes, departed from Mildenhall in the United Kingdom for Tel Aviv Israel. During the overnight flight to Israel, the two aircraft flew approximately 80-100 miles apart from each other and as high as 38,000 feet.

    The mission flight path took the scientists southwest of Mildenhall, over Lands End and out of the United Kingdom. The aircraft then turned south to fly over north central Spain, and then turned east to fly over Barcelona. The flight continued over Corsica, across the boot of Italy, over central Greece, and across the Mediterranean into Israel. ARIA and FISTA landed in Tel Aviv at 04:20 GMT Nov. 17.

    The scientists and crew members aboard the FISTA and ARIA had a very successful first night of their Astrobiology mission. In addition to observing meteors, the team took measurements of air glow, observed and recorded lightning over Spain, and saw Jupiter and Saturn clearly in the night sky. They also successfully demonstrated that live images of the meteors could be sent from the plane, over the TDRS satellite, to the Internet.

    The science team on the FISTA was thrilled with the collected data. "By the end of this first mission night we have already exceeded the number of meteors we observed with our mid-infrared instruments during the entire 1998 mission over Japan," said Peter Jenniskens, Leonid mission chief scientist.

    The mid-infrared spectrographs, contributed by the Aerospace Corporation, are being used to detect the unique fingerprint of complex organic matter - like that required for life - in meteors. The instruments are also expected to provide information on the formation of solid particles and the heat of the meteors as they enter the atmosphere.

    "A total of 10 meteors crossed the field of view of our spectrograph," reported George Rossano, a researcher on the FISTA aircraft. "I'm hopeful that these meteors will result in the first successful mid-infrared fingerprint of a meteor."

    On ARIA, the flux measurement team counted meteors without actually looking out the window to see them; researchers wore goggles that displayed images from cameras that were pointed out of the airplane's windows. The number of Leonid meteors and sporadic meteors counted by each team member was entered into a laptop computer.

    Jane Houston, a member of the flux measurement team and one of several amateur astronomers on the mission, explained how the team differentiated between Leonid and sporadic meteors. "The Leonid meteors radiate from the constellation Leo, while sporadic meteors fall randomly across the sky."

    Each of the team members' laptop computers was linked to a central laptop computer, and near real-time data indicating the total number of meteors counted was provided. "The methods developed to count meteors for this mission could revolutionize the way future meteor showers are monitored," claimed Kelly Beatty, another amateur astronomer on the flux measurement team.

    At the end of the night, the flux team reported observing approximately 14 sporadic meteors per hour and a Leonid zenith hourly rate of approximately 15 meteors per hour. The zenith hourly rate is the number of meteors an observer on the ground would see under perfect observing conditions.

    "These rates for Leonids are almost twice as high as those we would normally see the night before the expected peak," explained Dr. Jenneskins, "I'm optimistic this is an indication that we will see a good storm tomorrow night."

    The peak of the Leonid storm is expected at 02:00 GMT Nov. 18 over Europe and the Middle East. The international science team studying the Leonids will be flying from Tel Aviv to Lajes Airbase during the storm peak. It may be possible to see the Leonid meteor storm in the United States on the night of Nov. 17 (9:00 p.m. EST). However, best viewing may actually be in the predawn hours of Nov. 18.

    The Leonid Multi-instrument Airborne Campaign is an Astrobiology mission from NASA Ames Research Center at Moffett Field, CA. The campaign is jointly funded by the United States Air Force and the National Aeronautics and Space Administration. Astrobiology is an interdisciplinary field that studies the origin, evolution, distribution and destiny of life in the universe.

    For current information about the Leonid Multi-instrument Airborne Campaign, and to watch live Leonid coverage on the Internet, visit: http://leonid.arc.nasa.gov.

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