1996-98 Leonid Outburst Event Summary

• Leonid storm observing guides
  • Preparing for the 1998/99 Leonid Storms (P. Jenniskens, NASA/ARC)
  • Observing Hints for the 1998 Leonid Return (R. Arlt et al., IMO)
• Astronomical conditions in 1997-2000
  • Moon
  • The path of the Earth through the meteoroid stream
• Predictions of meteor activity 1997 - 2000
• Summary of observing conditions in 1998/1999
• Observing plans

View on Earth from the perspective of the Leonid shower at the time of passing the comet node.

Image by Peter Jenniskens, using software by John Walker. Satelite data are courtesy The Living Earth, Inc.

Astronomical conditions in 1997-2000

RA = 153.7 degree (J2000)
DEC = +21.9 degree (J2000), in constellation Leo
V = 71 km/s
Daily motion= +1.0 degree in RA and -0.4 degree in DEC

PATH OF THE EARTH THROUGH THE METEOR STREAM:

The following image (24K) gives a picture of the path of the Earth through the Leonid meteoroid swarm in the upcoming return (circles). The image is courtesy of Sky & Telescope and based on a paper by Yeomans et al. (1981) in ICARUS.

The path of the comet relative to Earth's orbit is found here.

Some predictions of meteor activity

Model calculations show that the most likely time of peak Leonid activity during the next several years is at a solar longitude of 235.2 +/- 0.05. This solar longitude corresponds to that of the peak of the 1966 Leonid storm, and is about 2 hours before the nodal crossing time.

ACCORDING TO: WILLIAM COOKE (1997):

Estimation of meteoroid Fluxes for the 1997-2000 Leonid storms by William Cooke, CSC/EL23 Marshall Space Flight Center.

ACCORDING TO : LANGBROEK (1997):

Based on recent Leonid observations.

Based on uncertain, but more extended numerical model of the meteor stream.

Based on the orbit of the comet and the passing of the comet's node. The meteor activitymay well be earlier or later.

Based on an uncertain numerical model of the meteor stream.

Based on an uncertain numerical model of the meteor stream.

Based on general interpretations of past Leonid observations.

OLDER PREDICTIONS ARE NOT LISTED HERE, because they are thought tobe even less certain.

Summary of observing conditions

• Time of peak:
18 - 23 h Universal Time (UT), most likely around 19.7h UT = 11.7 h PST = 2.7h Bangkok, Thailand.
• Expected meteor rates:
2000-10,000 meteors/hr per visual observer (peak at early morning hour: radiant in the zenith). Possible peak range: 100 (no storm) - 20,000
• Dust density outside atmosphere:
10E-23 g/cm3.
• Duration of the shower:
2x 1/e duration = 0.7 hours, total about 1.5 hours.
• Activity curve:
exponential increase and decrease of rates with time.
• Magnitude distribution index:
3.0±0.2 (numbers increase by factor 3 every magnitude)

• Best observing locations:
21±40 degree North, 120±45 degree East, best over China, Japan?, Phillipines, Vietnam and Thailand
• Radiant high enough above the local horizon at Latitute +15N:
01-06 hours local time
• Hours of dark sky:
until beginning of astronomical twilight
• Moon:
new Moon

• Time of peak:
0-5 h Universal Time (UT), most likely around 1.7h UT
• Expected meteor rates:
2000-10,000 meteors/hr per visual observer (peak at early morning hour: radiant in the zenith). Possible peak range: 100 (no storm) - 100,000
• Dust density outside atmosphere:
10E-23 g/cm3.
• Duration of the shower:
2x 1/e duration = 0.7 hours, total about 1.5 hours.
• Activity curve:
exponential increase and decrease of rates with time.
• Magnitude distribution index:
3.0±0.2 (numbers increase by factor 3 every magnitude)

• Best observing locations:
21±40 degree North, 30±45 degree East, best over Europe and northern Africa
• Radiant high enough above the local horizon at Latitute +20N:
01-06 hours local time
• Hours of dark sky:
until beginning of astronomical twilight
• Moon:
10 days old, will set during night