LEONIDS 2002

From Cosmic Mirror, 22 November 2002

LEONIDS SURPRISE AGAIN AS TWO FINAL STORMS BOTH REACH ABOUT 2500 METEORS PER HOUR

And while the two storms of 2002 rank only as the 3rd and 4th strongest of the five that pleased us in 1999, 2001 and 2002, there were again all the features we've come to expect from the Leonids: earthgrazing meteors while the radiant rose, bright meteors all over the sky and occasional fireballs with persistent trains (though not nearly as many as in 2001, let alone 1998). The peaks were very sharp, however, with full width half maximum times of only about 45 minutes each (in this respect, by the way, Jenniskens 'won').

This unusually spiky ZHR profile threw more than one observer into confusion as there wasn't the steady rise over several hours towards the peaks - when the radiant rose at the geometrically optimal sites in Europe and America, the rates were surprisingly low, only to take off after several hours. In Europe there was a pleasing encore, though, after the main peak from the 7-rev. trail as apparently two other, lesser dust trails kept the meteor rate from falling all the way back until sunrise. (Based on the IMO Shower Circular of Nov. 22 and the webmaster's own impressions on Tenerife)

Daniel Fischer

2002 November 22

-------------------------------------

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

-------------------------------------

A first activity analysis from the reports of 86 observers, who logged 19443 Leonids, is given below. The ZHR refers to a stellar limiting magnitude of +6.5, a radiant elevation of 90 deg, and counts of single observers. A population index of r=2 was applied, although the inspection of data suggests a large abundance of faint meteors, thus a larger r. The ZHRs would increase likewise.

The peak time of the first maximum is 04:10 UT with ZHR=2350. The second peak is found near 10:50 UT or a few minutes earlier with ZHR=2660. Both peaks occurred later than the predictions by about the same time lapse. The predictions of the Leonid stream model of Vaubaillon (WGN 30:5, 2002) are closest to reality according to this first analysis.

--------------------------------------
Nov  UT   Sollong   N   LEO   ZHR   +-
--------------------------------------
16  2000  234.257   2    10     19   6
17  0300  234.551   6    15      6   2
17  2200  235.349  13    96     37   4
18  0400  235.601  12    78     26   3
18  2000  236.273  21   431     98   5
18  2300  236.399  22   195    100   7
19  0000  236.441  26   330    101   6
19  0110  236.490  27   271    188  11
19  0140  236.511  24   218    201  14
19  0210  236.532  21   266    249  15
19  0220  236.539  20   332    305  17
19  0240  236.553  36   342    300  16
19  0255  236.564  16   157    275  22
19  0306  236.571  22   205    375  26
19  0316  236.578  28   329    497  27
19  0327  236.586  27   484    583  27
19  0335  236.591  48  1047    756  23
19  0343  236.597  20   412    930  46
19  0345  236.599  32   719   1162  43
19  0353  236.604  35   768   1344  49
19  0358  236.608  47  1341   1542  42
19  0402  236.610  36  1248   1966  56
19  0408  236.615  31  1335   2353  64
19  0413  236.618  17   912   2332  77
19  0418  236.622  30  1253   1995  57
19  0426  236.627  35   933   1367  45
19  0436  236.634  38   681    989  38
19  0447  236.642  24   416    635  31
19  0500  236.651  31   395    675  34
19  0518  236.664  50   505   1014  45
19  0535  236.676  22   189    572  42
19  0555  236.690  15    97    144  15
19  0620  236.707  15    87    142  15
19  0800  236.777  14   166    272  21
19  0905  236.823  21   217    307  21
19  0930  236.840  27    99    152  15
19  0947  236.852  21    72    267  32
19  1000  236.861  21   128    293  26
19  1010  236.868  31   192    707  51
19  1018  236.874  19   396    907  46
19  1023  236.877  15   134    965  83
19  1030  236.882  27   288   1364  80
19  1040  236.889  26   350   2108 112
19  1050  236.896  28   587   2656 110
19  1100  236.903  19   297   1061  62
19  1112  236.912  17   130    490  43
19  1135  236.928   7   184    366  27
19  2200  237.366   6    99    123  12
20  0500  237.660  11     4     10   5
---------------------------------------------

Solar longitudes refer to equinox J2000.0, N is the number of observing periods involved in the average ZHR, LEO is the number of Leonid meteors. The error of the ZHR is simply ZHR/sqrt(LEO) here. No special zenith exponent was applied to account for non-geometrical effects in radiant elevation correction.

We are very grateful to the enthusiastic community of meteor observers who have sent in their results, mostly through the online express form. All observers are encouraged to send their FULL DATA including magnitudes and possibly shorter time-bins for the counts within the next week.

(An error in the online form script has lead to erroneous output in geographical latitude and radiant elevation; the actual results presented here are not affected though.)

V. Krumov, M. Gyssens, R. Arlt

November 21, 2002

Forward Scatter Meteor Observations of Leonids 2002

Observer:    Ton Schoenmaker
Location:    Roden, Netherlands (06 26' E, 53 08' N)
Frequency:   60.500 MHz
Transmitter: French TV channel L3 (video); transmitter in Carcassonne (100 kW),
             distance ~1100 km             
Antenna:     3-elements horizontal Cushcraft 50 MHz Yagi tuned to 55.3 MHz;
             geographical azimuth 195 degrees (SSW) 
Receiver:    Yupiteru MVT-9000 in USB mode; sensitivity 0.5 uV at 12 dB S/N
Observing:   800 Hz audio signal from earphone socket was rectified, digitised 
             and fed into a PC via the parallel computer port. HP VEE was used 
             to process the digitised signal and to store 15-minutes counts of
             reflections stronger than 0.22 uV (-120 dBm). Also for all 
             individual meteors date, time, duration (dead time) and maximum 
             signal are stored.

November 19, 2002

Leonids from Northern California

Bill Smith

Nice Meteor Show in Galveston County

Jim Oberg
www.jamesoberg.com

Leonids from Clermont, FL

David Zurcher

2002 Leonids a bust from the streets of Brooklyn

R. Paul Martin

Leonids Arrived in Scotland

Alex Stephens Jr
North Lanarkshire weather
Wishaw, North Lanarkshire, Scotland

Leonids from Manchester!

Paul Richardson
Leigh
Lancs

Leonid image from Cumbria

Robin Leadbetter
(ROBIN'S ASTRONOMY PAGE)
NW Cumbria

Leonids: Northumberland

Adrian Jannetta

Leonids Double Maximum 04:00 and 04:30

Paul Clark (UK)

Leonidi: che c**o

Roberto Haver

Leonids

Jan Exner

Leonids: Australia

Timo Karhula

Get detailed predictions for a city:   Meteor Storm Forecast
Photographing the Leonids? Go to: Meteor Photography Tips
Observing the Leonids? Go to:       Leonid Observing tips

Observations and/or photographs? Leoniden2002@astronet.nl

General information:

NASA Science News for November 18, 2002

A Spaceship Among Meteors

FULL STORY

NASA Science News for November 16, 2002

The Leonids TV Show

FULL STORY

* * * SKY & TELESCOPE's SKYWATCHER'S BULLETIN - November 12, 2002 * * *

THE LEONIDS ARE COMING

NASA Headquarters, Washington

November 14, 2002

NASA PREPARES FOR "LAST CHANCE" METEOR SHOWER

"Even with the full moon, this year's Leonids will probably be better than any other for the next hundred years," said Dr. Don Yeomans, an astronomer at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "If you're ever going to see them, this might be the year to try," he said. NASA is taking advantage of the event for several research efforts around the world.

The shower is predicted to have two peaks, each a couple of hours long, during which the most meteors can be seen. The shower's second peak, most prominent in North American skies, is expected at around 5:30 a.m. EST Nov. 19, and promises the rare spectacle of a few meteors every minute or even more. "Observers in good locations away from city lights might see a few hundred per hour. You'll only get to see the bright ones because the moonlight will wash out the ones that aren't as bright," said Yeomans. Last year, observers did not have to contend with the Moon and saw meteors at a pace of several hundred per hour.

An earlier peak is expected over Europe and Africa the night of Nov. 18, and observers in North America might see a few grazers -- meteors skimming the top of the atmosphere -- from this first peak starting around 11:30 p.m. EST Nov. 18.

The Leonids are grains of dust from comet Tempel-Tuttle colliding into the Earth's atmosphere. Most Leonid particles are tiny and will vaporize very high in the atmosphere due to their extreme speed (about 44 miles per second, or almost 71 km/sec), so they present no threat to people on the ground or even in airplanes. As it progresses in its 33-year orbit, the comet releases dust particles every time it comes near the Sun. Earth intersects the comet's debris trail every year in mid-November, but the intensity of each year's Leonid meteor shower depends on whether Earth ploughs through a particularly concentrated stream of dust within the broader debris trail.

The dust that Tempel-Tuttle shed in 1866 forms the stream predicted to give Americans a good show this year. Last year, people in Asia saw the plentiful collisions within that stream. A dust stream from 1767 provided last year's peak hour of viewing in North America and will provide this year's peak hour of viewing in Europe. After 2002, Earth won't hit either of those streams again for decades to come, and is not predicted to encounter a dense Leonid stream until 2098 or 2131.

The golden rule for watching the Leonids -- or any meteor shower -- is to be comfortable. Be sure to wrap up warmly -- a sleeping bag placed atop a lawn chair facing east is a good way to enjoy the show. Put your chair in a clear, dark place with a view of as much of the sky as possible. Don't stare at any one place -- keep your eyes moving across the sky. Most Leonids will appear as fleeting streaks of light, but watch for the bigger ones that produce fireballs and trails -- some trails will remain visible for several minutes or more.

The Leonids get their name from the constellation where they appear to originate; the meteors will be radiating from the Sickle pattern in the constellation Leo the Lion, which will be rising out of the east-northeast sky. Don't look directly at the constellation, but at the area above and around it. And, though you don't need them to see the Leonids, a pair of binoculars could come in handy.

Researchers think meteors might have showered the Earth with the molecules necessary for life's origin. A two-aircraft campaign, led by astronomer Dr. Peter Jenniskens of the SETI Institute and NASA's Ames Research Center, Moffett Field, Calif., will investigate this possibility. "We are looking for clues about the diversity of comets and their impact on the chemistry of life's origin on Earth," Jenniskens said.

"We are eager to get another chance to find clues to two puzzling questions: What material from space rains down on Earth, and what happens to the (meteor's) organic matter when it interacts with the atmosphere?" said Dr. Michael Meyer, senior scientist for astrobiology at NASA Headquarters in Washington.

On Nov. 15, a team of 42 astrobiologists from seven countries will depart from southern California's Edwards Air Force Base on a mission to Spain to observe this year's two Leonid storm peaks. The DC-8 Airborne Laboratory, operated by NASA's Dryden Flight Research Center, Edwards, Calif., will carry high-speed cameras; a radio receiver to listen to upper atmosphere molecules; and a team of meteor observers, who will keep track of the meteor activity for satellite operators concerned about impact hazards.

"This final deployment of the Leonid Multi-instrument Airborne Campaign program promises an important and unique database for the development of instruments targeted at in situ sampling of cometary materials and for the future definition of comet missions," said Dr. John Hillman, lead scientist for planetary astronomy at NASA Headquarters. "It is hoped that these scientific data will provide new insights for the comparative studies of comets," he said.

Although the meteors are harmless to people, there is a slight chance that a satellite could be damaged if it was hit by a Leonid meteoroid. The meteoroids are too small to simply blow up a satellite. However, the Leonids are moving so fast they vaporize on impact, forming a cloud of electrified gas called plasma. Since plasma can carry an electric current, there is a risk that a Leonid-generated plasma cloud could cause a short circuit in a satellite, damaging sensitive electronic components.

NASA's Goddard Space Flight Center, Greenbelt, Md., is responsible for controlling a large number of satellites for NASA and other organizations and is taking precautions to mitigate the risk posed by the Leonids. These include pointing instrument apertures away from the direction of the Leonid stream, closing the doors on instruments where possible, turning down high voltages on systems to decrease the risk of a short circuit, and positioning satellites to minimize the cross-section exposed to the Leonids.

Minimizing the threat meteoroids pose to satellites is the second major area of NASA's Leonid research. From five key points on the globe and from the International Space Station, NASA researchers will use special cameras to scan the skies and report activity around the clock during the Leonid shower. Led by Dr. Rob Suggs of the Engineering Directorate at NASA's Marshall Space Flight Center in Huntsville, Ala., the research is part of a long-term goal to protect spacecraft from potentially damaging meteoroids.

Using "night-vision" image-intensifier video systems and sky-watchers outfitted with Palm computer software developed to record visual counts, NASA engineers and astronomers will record their observations for later analysis. Another tool at Marshall's disposal is "forward-scatter radar" -- an early warning system built by Suggs, Dr. Jeff Anderson, also of Marshall's Engineering Directorate, and Dr. Bill Cooke, an astronomer at Marshall.

"Our system is pretty simple," said Suggs. "We use an antenna and a computer-controlled shortwave receiver to listen for 67 MHz signals from distant TV stations." The transmitters are over the horizon and normally out of range. When a meteor streaks overhead, the system records a brief ping -- the echo of a TV signal bouncing off the meteor's trail. Like the image-intensified cameras, this system is capable of detecting meteors too dim to see with the unaided eye.

The research data from the Leonids shower will be analyzed to help NASA engineers refine their forecasts for spacecraft; by better determining where, when and how the meteors will strike, NASA can improve protective measures to prevent or minimize damage to spacecraft.

Marshall Space Flight Center, Huntsville, AL

November 12, 2002

'Catch a shooting star!'

NASA engineers to scan for Leonid meteor shower Nov. 18-19

Sky-gazers in North America and Europe should be able to "catch" as many as one meteor every 6 to 10 seconds -- even with a full moon shining -- during the peak of the Leonid meteor shower, which occurs when Earth passes close to the orbit of the Comet Tempel-Tuttle and debris left in the comet's path.

Led by the Engineering Directorate at NASA's Marshall Space Flight Center in Huntsville, Ala., the research is part of a long-term goal to protect spacecraft such as NASA's Chandra X-ray Observatory from potentially damaging meteoroids.

"Stargazers should see a great show, even though the full moon will cut visibility about 75 percent," said Dr. Rob Suggs, the Space Environments Team Lead. "For the past three years, we've had some astounding Leonid showers. However, this may be the last opportunity in our lifetimes to see a 'storm' of Leonids. Predictions lead us to believe this could be the 'grand finale' until 2133."

Using "night-vision" image intensifier video systems and sky-watchers outfitted with Palm computer software developed to record visual counts, NASA engineers and astronomers will record their observations for later analysis.

Despite what their name suggests, "shooting stars" are not stars at all; they are meteors. Meteors are produced when bits of cometary or asteroidal debris in space, usually between the size of a sand grain and a pebble, enter the Earth's atmosphere and burn up, creating a brief -- usually white -- streak of light.

The Leonids were named such because they appear to radiate out of the constellation Leo. The material crossing Earth's path this year was ejected from the Comet Tempel-Tuttle at least 100 years ago. Meteor viewers in the United States, for example, will see material ejected from the comet in 1866.

NASA engineers have provided meteor shower rates for many cities around the world through the NASA Web site: www.SpaceWeather.com sponsored by Science@NASA

Astronomer Mitzi Adams of the Marshall Center also will provide updates Nov. 18 on the progress of the Leonids to SpaceWeather.com .

NASA's concern, however, isn't the view. Even though today's satellites are engineered to withstand a smattering of meteoroid strikes, by determining where, when and how the meteors will strike, NASA can take protective measures to prevent or minimize damage to spacecraft.

Because the stream from Tempel-Tuttle hits the Earth almost head-on, the Leonids are among the fastest meteors known -- entering the Earth's atmosphere at 44 miles per second.

Since the Chandra Observatory must travel through the Leonid debris field, controllers at its Operations Control Center in Cambridge, Mass., will make sure the satellite is pointed in the exact opposite direction as the incoming meteors. They will angle the solar arrays to protect the sensitive back of the arrays and minimize the surface area presented to the meteor direction.

Protective measures can range from turning a satellite so it faces the direction of minimal exposed surface area, to shutting down a spacecraft's electronic operations until the storm has passed.

"When a meteoroid hits a satellite, it can heat the impact site to thousands of degrees Kelvin -- rivaling the surface temperature of the Sun," Suggs said. "Usually the entire meteoroid is vaporized along with a tiny bit of the spacecraft."

Considering that meteors are so small, their potential for damage can be surprising when their speed is considered.

"They're small, but they move very fast -- about 45 miles per second (71 kilometers per second)," said Dr. Bill Cooke, an astronomer at the Marshall Center.

Cooke says the research data from the Leonid shower will be analyzed to help NASA engineers refine their engineering forecasts for spacecraft.

According to Cooke, sky-gazers could see up to 600 meteors per hour if they are away from city lights and the sky is clear. In the Eastern United States, the shower is predicted to peak near dawn, while in the Western United States, it is expected to peak around 2:30 a.m. PST. However, the "show" will start Nov. 18 about 10:53 EST with the Leonid "grazers" -- meteors not dropping into the Earth's atmosphere, but instead grazing the atmosphere. Grazers appear as reddish meteors that advance east to west across a large part of the sky.

The NASA researchers will monitor the storm from five locations, each selected based on meteor forecasts and the area's climate. Sites include Huntsville, Ala.; Calar Alto Observatory in southern Spain; Teide Observatory in the Canary Islands; Apache Point Observatory in southern New Mexico; and Kitt Peak National Observatory in southern Arizona.

Another tool at Marshall's disposal is "forward-scatter radar" -- an early warning system built by Suggs, Cooke and Dr. Jeff Anderson, also of Marshall's Engineering Directorate.

"Our system is pretty simple," said Suggs. "We use an antenna and computer-controlled short-wave receiver to listen for 67 MHz signals from distant TV stations."

The transmitters are over the horizon and normally out of range. When a meteor streaks overhead, the system records a brief ping -- the echo of a TV signal bouncing off the meteor's trail. Like the image-intensified cameras, this system is capable of detecting meteors too dim to see with the unaided eye.

The Marshall Center has also provided Leonid forecast information to operators of spacecraft such as Chandra to help prepare for a meteor shower. "By comparing the meteor shower predictions to the actual meteor counts, we are laying the groundwork to improve forecasts in the future," said Suggs.

How to view Leonids:

ESA

14 November 2002

ESA's shortcut to a comet

Read more

Leonids in previous years: