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LEONID DAILY NEWS: December 23, 2000

Total meteor activity during Ursid outburst

This record of total meteor activity was obtained by Esko Lyytinen using forward meteor scatter. Click on the graph for an overview of the reflections. A similar record by Ilkka Yrjola of Kuusankoski, Finland, is shown below. Both data sets clearly demonstrate the Ursid outburst.

Radio meteor reflections measured by Yrjola


Radio forward meteor scatter observations - Finland.

The Ursid shower did flare up significantly last night between 5 UT and 9:30 UT, with a peak around 7:2010 UT according to foreward scatter observations by Esko Lyytinen (shown above). The forward scatter technique counts meteors by listening to reflected signals from faraway radio and tv transmitters.

Ilkka Yrjola of Kuusankoski, Finland, reports similar results. His counts (right) are shown after subtraction of the daily sporadic background. Yrjola is located about 100 km from Lyytinen and collects reflections in the opposite direction.

Other confirmations from radio-MS observations were received from Sadao Okamoto, Sabae City, Japan, Masayoshi Ueda of Japan, Ton Schoenmaker of Roden in the Netherlands, and Wayne Itano of Boulder, CO.

Video and visual observations - California.

The shower was observed by us from California, using video imaging and spectroscopy techniques. Present were Peter Jenniskens, Ming Li and Duncan McNeill at a site near Parkfield, and Pete Gural, Mike Koop, Mike Wilson, and Chris Angelos at the San Antonio Lake campground near King City. GlobalStar provided a satelite telephone link. Local weather allowed observations between about 5:30 and 11:20 UT. Six intensified cameras at each site recorded the variation of flux and Ursid light curves.

Some very minimal (!) visual observations taken in between operations of equipment are reported below and suggest a ZHR of about 50 shortly after the peak. This compares to a peak ZHR of 80 for the Perseid shower in summer.

Obs: Peter Jenniskens
Loc.: Parkfield, California (about 120.0 Deg. W, +35.9 deg. N)
Date: December 21-22, 2000

UTC           Teff  Lm   Urs  Spo   ZHR(Urs)

08:07-08:19   0.20 6.2   4  3       5025
08:31-08:52   0.35 6.2   4  2       2714
09:13-09:32   0.32 6.2   2  3       1410
10:14-10:55   0.69 6.2   6  12      177


We've analysed the first video tapes of our observations in California and find the (preliminary) rate of Ursids shown here. These were gathered by Peter Gural and Peter Jenniskens from a visual scan of the tapes of three of our intensified video camera's at Parkfield. 8 more cameras to go. We also detected at least one Ursid spectrum at 08:24:57 UT, covering the wavelength range from about 400 to 850 nm, the meteor of which was imaged from both observing sites. 19 double station Ursids thus far after comparisson with part of the tapes from an aligned intensified video camera at San Antonio Lake.

The peak time and duration of the shower appear to be very similar to our predictions , with a peak time at 7:29 UT (1405 trail) and a possible contribution from the 1392 trail at 8:38 UT. The observed maximum is in between. Further confirmation of the models and information on the relative contributions of both trails will follow from further analysis of the observational data.

Ursid counts from three intensified video cameras

Ursid meteor passes M44

Top: Ursid counts from three intensified video cameras positioned at Parkfield, CA. Open symbols show visual counts by Dutch (left) and Japanese (right) observers (Updated: Dec. 27).

Left: A "Christmassy" Ursid meteor passes M44, the Beehive cluster, also called the Manger, in the constellation Cancer. Image courtesy: Peter Jenniskens, California


US and Canadian observers were best located for the event, although European observers Marco Langbroek of the Netherlands and Sirko Molau and Rainer Alt of Germany report observing the onset of the shower at 5-6:15 UT, at which time the ZHR was about 20. Japenese observers witnessed the final part of the profile.

Among scientific efforts, Bob Hawkes from Mount Allison University in New Brunswick, Canada, reports video imaging during relatively low Ursid rates between 4:15 and 6:00 UT, prior to the peak, after which clouds interfered with further observations.

Previous news items:
Dec. 23 - Ursid outburst confirmed
Dec. 18 - Dec 22 Ursid outburst
Nov. 20 - A bacterial fingerprint?
Nov. 15 - HCN disappears mysteriously
Nov. 14 - Meteor shower from space
Nov. 13 - Organic fingerprint
Nov. 12 - Train airglow chemistry
Nov. 11 - Hard bits and persisting glows
Nov. 10 - Meteoroid debris detected
Nov. 09 - New meteor picture
Nov. 08 - Spin city
Nov. 07 - Meteors affect atmospheric chemistry
Nov. 06 - Listen to this!
Nov. 04 - Fear of heights?
Nov. 03 - The pale (infra-red) dot
Nov. 02 - Twin showers
Nov. 01 - Leonids approaching Earth
Oct. 31 - Prospects for Moon Impact Studies
Oct. 30 - Comet dust crumbled less fine
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Results of this work were published in Icarus.

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