Leonid 2000 Campaign
Some first results
Station Almodôvar (Portugal), Dutch Meteor Society
(Koen Miskotte, Carl Johannink and Marco Langbroek)
and selected American results
(update 28/11/2000)
logo: Robert Haas
NEW- NEW!!
(update 28/11/2000) - below a plot combining our data from Portugal, Europe with those obtained by Norman McLeod (AMS) from Florida, USA and Pierre Martin from Quebec, Canada. Note how the onset of the peak over North America already is visible in the European data. Two major syymetric peaks (3:25 UTC and 7:20 UTC) are visible, with a sub-peak at 2:00 UTC (for a graph with individual results of Martin and McLeod compared, click here)
Hunting for Leonid peaks in Portugal
B
ecause of the highly unfavourable weather predictions for the Netherlands and wide surroundings, Carl Johannink, Koen Miskotte and I decided on the 15th of November to book a last-minute flight from the Netherlands to Portugal. We left November 16 and returned November 19.O
ur last-minute "crash-campaign" (Dutch observers’ jargon for: a desperate last-minute long-distance travel in search for clear skies) to Portugal turned out to be a very wise decision, because southern Portugal happened to be one of only few locations in Western Europe which did experience clear skies around the maximum. And so did we.S
outhern Portugal has a scenic landscape consisting of low mountains and hills with agricultural fields, vineyards, characteristic scattered twisty cork-oaks that add a peculiar touch to the landscape, and small scenic hamlets and villages. We arrived in the late afternoon and therefore had to travel with our rented car in twilight and darkness to reach our destination. The (non-illuminated) roads were winding up and down next to steep valleys, with hairpin-turns and a bad road surface. Suddenly, Carl had to step on the brakes with force when a large piece of rock emerged from the darkness into our headlight cone, just on the middle of the road. Then, we reached our destination.B
oth November 16-17 and 17-18 delivered us clear skies. We observed from Almodôvar, a small village some 75 kilometers north of Faro. A year before, other DMS observers had been there and, while picking an agricultural field about a kilometer outside the village for our short November 17 session because we could not find the mentioned location in the darkness, we basically used the same observing field as they did the next night. This was a scenic spot, consisting of a chapel (Sancta Amaro) on a large hill about 0.5 to 1 kilometer from the village. This chapel on the hill was the highest point in the landscape, offering a beautifull vista in daylight. That it was situated well above the rest of the landscape proved rewarding: on the night of November 18 fog developed in the valley capped by a sharp inversion layer, but our hilltop was located some tens of meters above the upper edge of the fog blanket leaving us in clear skies! Only the last 15 minutes of the night, already in twilight, the fog came up the hill. We used the surrounding low walls of the chapel to block direct vision of the moon. Sky conditions were excellent, especially given the disturbing moonlight: I typically had a limiting magnitude of +6.4 nothwithstanding the moon!November 16-17
Rates already were mildly enhanced on November 16-17 (see figure below), with rates about twice that of normal annual rates and a suggestions of a slight rise over time. This probably belonged to a broad B=6 peak that according to radio-MS data by Ton Schoenmaker as well as the preliminary visual profile of the IMO, occurred near passage through the cometary orbit node. It probably is the so called "filament" which formed the background to the storm peak in 1999. The population index was 2.83 ± 0.27 calculated over the full observational interval for the range of magnitude –1 to +4.
November 17-18: What a great show !!!
On November 17-18, our efforts were rewarded with a strong enhanced activity lasting many hours! Rates reached ZHR’s in the order of 300-340 during our observing interval, which featured a more or less continuous high-level activity with the suggestion of at least two peaks in it, as well as the onset of a third peak (that which peaked over the US near 7:20 UTC, 30 minutes before the predicted peak time) at the end of the night. Personally, I counted over 500 Leonids this night with peak raw rates of 6 to 9 per minute close to 3:30 UTC. The predicted peak at 3:44 UTC, according to our data happened earlier in reality: near 3:25 UTC. Thus, both the 8 revolutions and 4 revolutions dust trails peaked earlier than predicted by Asher & McNaught and Lyytinen, as suggested by the data currently available. The deviations are up to 20-30 minutes, which is larger than the 10 minute accuracy attributed to these predictions. In addition, none of the predictions for the strength (ZHR’s) of the peaks was correct, neither those by Ferrin, Asher & McNaught or Jenniskens, except for the predictions by Lyytinen. The peak near 7:20 UTC indeed appears to have, as calculated from data obtained by Pierre Martin (Quebec, Canada) and AMS observer Norman McLeod (Florida), a maximum ZHR in the order of 800, see the activity profile on the top of this page. This is close to the value (700) predicted by Lyytinen.
There is some suggestion in our profile of an unpredicted secondary peak (with ZHR near 300) near 2:00 UTC.
The population index was 2.58 ± 0.12 calculated over the full observational interval for the range of magnitude –1 to +4 (later, we will look in detail for possible variations in population index over time).
This night witnessed several nice bright Leonids, including some smashing fireballs. Our team observed a –6, a –7 and a –8 Leonid, the latter featuring 10 minutes of persisting train. This night ranks third on my private list of spectacular Leonid events, after the 1999 storm and the 1998 fireball shower. I thoroughly enjoyed it!
Text written 26 November 2000, revised 28 November 2000, by M. Langbroek, Dutch Meteor Society
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