LEONIDS 2002 - PRELIMINARY RESULTS|
Javor, Jure and I decided quite a long time ago that we would observe this year's Leonids from Spain. Booked flights, rented cars, pretty much did everything, just to cancel everything due to a bad medium range weather forecast. Back to square one. Rent a van, wait for the last minute and drive to whereever necessary. We were joined by three other observers: Nina, Dunja and Daniel. In the morning of Nov 18th we set out for what would be a 900 km drive to Nice in France. Werfried Kuneth voulenteered as 'mission control', passing us weather info via mobile phone every 30 minutes. Thanks Werfried!! We reached Nice around 21h UT and the monotonous cloud cover that had been present for most of the drive began to break in places. Clouds were relatively low and we could see that there wasn't any high cloud cover above it.
We then decided to turn north towards the Alps, the mountain village of St. Martin-Vesubie seemed a good destination with about 1500 m altitude. After an hour's drive the sky we reached St. Martin. It was absolutely magnificent: the snow covered peaks bathed in moonlight and a completely clear sky! But the horizon was a bit less satisfying - reaching as high as 40 degrees in the north. After about an hour's search we found a suitable observing spot on a ski slope on Pic de Colmiane.
Pic de Colmiane: observing location of the Leonids 2002 MBK Team expedition.
As soon as I stepped out of the car (22:55UT), a blue -3m sporadic fireball shot through Ursa Major. We then proceeded to set up our equipment: all-sky camera, photo camera battery and visual stuff. Midway through preparations a -5m green Taurid appeared in the northwest. Now it was Murphy's time to join us. First the camera battery shutter failed. We couldn't isolate the problem, let alone fix it. Then the all-sky camera mirror (60 cm diameter acrylic glass) began to dew and then frost. All-sky was soon history. Javor then mounted his Mintron camera on a photo tripod - guess what, it worked! Then the sky suddenly lit up as a brilliant green -12m Taurid fireball exploded in the zentih, producing a shower of orange fragments.
A video clip of a bright Leonid at 00:57 UT. The field of view is about 45°×35°.
Everything was going just fine (ignoring all the failed equipment) when... FOG began to form just around our altitude. In a matter of minutes most of the sky was covered and we were in despair! Javor, Dani and I decided to walk (or rather climb!) the steep ski slope to the peak and see if there was any chance of clear skies in the vicinity.
10 minutes and a gallon of sweat later we were at the peak (1790m). There was a cottage at the top with a large viewing platform. The sky was clear - the fog was below us. We quickly ran down to get our equipment. The fog disapeared in the meantime. Also a 50 degrees long -3m Leonid fireball shot through Auriga. Even though it was clear when we reached the van, we rather walked to the peak again, just in case fog returned. It didn't. The peak was covered with grass and rocks. The snow line was several hundreds of meters above us.
I started observations at 01:18 UT. I was facing east towards Ursa Major and Lynx, with the cottage several tens of meters behind me. With the Moon well out of my FOV the LM was very good at 5.8. There was just a slight breeze. As usual I began observing outside my sleeping bag, but the low temperatures (-5°C or less) forced me to crawl into the bag rather soon. Leonids were immediately apparent, coming at a rate of about one per minute. Javor and Jure Z began making exposures. A little later, at 2:16:38 UT, just after Jure had filed a formal complaint about the lack of fireballs a green -6m Leonid shot through Ursa Major, right throught his photographic FOV. He was *quite* happy with that (you should listen to the tapes...). Another -3m Leonid appeared at 2:32 UT. By then the Leonids were coming at a rate of two or three per minute. Another -3m Leonid at 2:45. We had a minor incursion by fog for three minutes starting at 2:55, lowering the LM by .5 mag. Then at 03:00:03 UT the northern sky lit up as a brilliant -10m green Leonid exploded near Denebola, leaving a vividly green train, that would persist in bright moonlignt for more than 9 minutes.
-1 magnitude Leonid at 030941 UT close to Jupiter. Exposed from 030918 to 031042 UT with 37/2.7 lens.
The third hour started at 3:18 UT. With 4 Leo per minute the show was nice, but I was beginning to wonder if perhaps it was running behing schedule or below predictions. Also the Leonids were much fainter than last year, negative magnitude shower members were rare. The rate was slowly rising, by 3:30 UT - only 30 min before the predicted peak - there were 5 per minute. By 3:40 UT the rate had sharply increased to 15 per minute. A -3m Leo fireball in Orion at 3:40:59 left a 48 second train. By 3:50 the rate increased modestly to 18 Leo per minute. 4:00 UT and there were 25 per minute. A spike in rates was reached at 4:04 with 47 Leo per min, flanked by lower rates of 30 and 32 Leo per min. For the next seven minutes the rates hovered around 30 per minute. The peak was reached around 4:12 UT with rates above 40 Leonids per minute for four minutes (top rate 46 per minute). I managed to record magnitudes all the way to the peak. Then I didn't record for four minutes AFTER the peak, when I though I couldn't keep up if the rates kept increasing. So, there is one minute with a meager 19 Leonids with no magnitude data. You idiot... Only one fireball appeared in this time, a -3m Leo at 4:00. All this time there were very few bright Leonids. Most were +2m to +4m. Many short Leonids appeared near the radiant. Brighter Leonids that were close to the radiant often left a 'thick' greenish train that *immediately* went serpentine. I wonder if this effect is present also with trains of longer meteors further away from the radiant, but is not visible because we see the trains more perpendicularly?
-4 magnitude Leonid at 034117 UT. The bright star near meteor is Alphard (Alpha Hydrae). Exposed from 033804 to 034135 UT with 37/2.8 lens.
By 4:30 the Leonid rates had diminished to 12 per minute. 15 minutes later there were about 8 per minute. At 04:49:00 another -10m Leonid, this time orange, appeared in the northwest, followed by a -4m Leonid only 4 seconds later. For the rest of official observations, until 5:16 UT the rates remained above 4 per minute. LM was 6.0 for the final 30 minutes. Two more bright flashes were seen. We remained at the top of the mountain for another half hour. Javor and Jure made some nice pictures of the breathtaking surrounding landscape. I kept looking in the sky :) And I saw two more -5m Leonids.
Analysis of observations from Pic de Colmiane in France show a peak ZHR of 3300±150 at 4:10±3min. ZHR was above 1000 for about 45 minutes. No secondary peaks are apparent.
Remark: ZHR values were calculated with r=2.0 and gamma=1.0. ZHR values might differ from those calculated by IMO due to a smaller observation sample and individual observer perception coefficients. Observations were made from Pic de Colmiane (1771m).
Leonids 2002? Oh yeah! Definitely excellent. We had luck with the weather and found perfect skies. The rates were excellent. Compared to 2001 7-rev peak, this year the peak was much shorter and sharper and the meteors much fainter. Inital ZHR calculations by our team suggest top ZHR 3300 and FWHM of only 40 minutes. My magnitude data suggests r=2.6, while that of Jure and Javor suggests r=2.4. In 3.95h teff I saw a grand total of 1775 Leonids, 1 Alpha Monocerotid, 2 Taurids and 12 sporadics.
A toast after another successful campaign.
Papers published about Leonids 2002:
Jure Atanackov, Javor Kac, Jure Zakrajsek. Leonidi - od znanilcev konca sveta do tezko pricakovanega spektakla. Spika 10-11 (2002): 472-6, 90-2
Jure Atanackov, Javor Kac, Jure Zakrajsek. Leonidi 2002. Spika 10-12 (2002): 540-1
Rainer Arlt, Vladimir Krumov, Andreas Buchmann, Javor Kac, Jan Verbert. Bulletin 18 of the International Leonid Watch: Analysis of the 2002 Leonid Meteor Shower. WGN, Journal of the IMO 30-6 (2002): 205-12
Javor Kac. Opazovali meteorski dez Leonidov. Dobro jutro 2-8 (2003): 10
Javor Kac, Jure Zakrajsek, Jure Atanackov. Visual observations of the 2002 Leonids by the MBK Team. WGN, Journal of the IMO 31-1 (2003): 5-7
Jure Zakrajsek, Javor Kac, Jure Atanackov. Radio observations of the 2002 Leonids from Slovenia. WGN, Journal of the IMO 31-1 (2003): 13-5
Javor Kac. Observations of the 2002 Leonids by the MBK Team. Proceedings of the International Meteor Conference, September 19-21, 2003, Bollmannsruh, Germany (2004): 53-8