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The mind-blowing video clips of the 2002 Leonid shower August 11, 2007

Posted by dorigo in astronomy, personal, science.
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Darn. A moonless 12th of August happens only once every three years, and – exactly as it happened three years ago – the sky is quite cloudy above my head. The Perseid meteor shower peaks unfavorably in the morning for European observers this year but still, with a clear night from my favorite observing site here in the italian dolomites, I would expect to pocket at least a hundred meteors in a few hours of observation.

Instead, I will probably be sleeping tonight and tomorrow night. You might well ask, so what ? Perseids are very well studied, we know close to everything about their orbital distribution and other details, and the data observers acquire each year, which are then collected by astronomical unions such as the UAI (in Italy) or the IMO (internationally), and then analyzed, are not going to be affected by the absence of my own risible contribution much.

Agreed. Nonetheless, I would be happy to spend four or five hours in the darkness of Passo S.Antonio, 1480 meters above sea level, in the cold and damp, straining my neck and ruining my sleep cycle, just to stare at the meteor shower. Occasionally, I would get to see a very bright meteor, which I would record in all its details. Otherwise, I would just collect 5-minute counts of the perseids, or track on gnomonic maps of the sky non-perseids, noting hour, brightness, duration, color. Most of all, I would just enjoy the show. It is a passion cultivated through more than thirty years now.

This year I will console myself – and maybe cheer a few readers up – with video clips I took in the fall of 2002, when I was treated with a huge shower of the Leonid meteors. On the night of November 17th I traveled 300 miles with two other astroamateur nutcases through Italy, in search of a cloudless spot. We ended our search on the coast of Tuscany, off the Isola del Giglio, and we saw a real show. I had a Sony digital recorder with me, and took three hours of footage. During the peak of the shower, when more than twenty meteors per minute were visible, the camera took some very nice sequences. You can see four of them here (690kb mpg), here (4.1Mb mpg), here (5.2Mb mpg – 10 bright tracks in 40″) and here (634kb mpg).

In the end, I found 173 tracks recorded on video. A little analysis allowed to determine the Zenith Hourly Rate (ZHR) of the shower as a function of time, as shown in the graph below (on the x axis are successive 5′ intervals, on the y axis is the ZHR). Remarkably, the data from thousand of observations collected by IMO (blue curve) is in excellent agreement with the points obtained by my own analysis!

Showers such as the one of 2002 are rare. We are talking about two, three hours of very high rates every few years, if you are sitting in the right spot on Earth (when it is dark, and when the sky is clear, and when there is no moon!) – and often we do not get to know beforehand whether there will be one. If you do not chase meteor showers, you are unlikely to see a big one in your whole life, no more than you are of seeing a tornado – if you don’t live in Oklahoma, that is. Seeing a tornado is something I would both love and dread. Maybe one day I will chase one of them as I do meteor showers…

Comments

1. jasonwer - August 13, 2007

Reminds me back in 2002 – on the night of peak activity, my area was clouded out. I checked the sky at 8pm then 10pm and then midnight but not one star to be seen…

After watching a late night movie I decided at 2am to get some sleep. I took one last look at the sky expecting 100% to be disappointed when all I could see was a sky full of meteors. Luckily a large hole in the clouds had opened up directly above me – meteors would appear in front of me and arc overhead so I’d have to turn my head 180 degrees to follow them. After turning back there would be more meteors appearing.

After about 20 minutes the hole in the clouds had moved so I got in my car and headed west a few kilometres to follow it but it disappeared. But those 20 minutes of Leonid viewing will be remembered for a very long time. The best astronomical fun to be had without a large telescope I think.

– Jason

2. dorigo - August 13, 2007

Hi Jason,

yes, many astro-aware people have their own personal story to tell about that night and about those of 1999 and 2000. My brother was driving in the night and was not aware of the shower, but was treated by a huge show through the window of the car. In 2000, I was on a plane traveling from Chicago to Frankfurt, and saw 403 meteors in 2 hours from a window… It would be fun to collect some testimonies in a site.

And you are right, few things like a huge shower put up a astronomical show enjoyable without a scope.

Cheers,
T.

3. changcho - August 15, 2007

Well, I observed the Perseids a couple of nights ago with my daughter and my sister from a not-too-high mountain site in California. We observed Aug. 13th, 0:00-01:00 hrs local time (Aug. 13, 07:00-08:00 UTC) and I saw only 17 Perseids. Mind you, the radiant was a bit low (~30 deg.), but we could not observe more than past 1:00 am because we were sleepy and cold! I also saw what at first I thought were 4 sporadics, but these seemed to come from the region of Cygnus, so I think these were kappa cygnids. I’ll send my obs. to the IMO soon.

As far as the Leonids go, Nov. 17th, 2001 was a spectacular night! We observed them from Mt. Hamilton, California (where Lick observatory is located) with several friends. There were several people all over the mountain as many were aware of the approaching Leonids storm, I recall that about 3:00 am local time we lost count as then were were seeing them at a rate of 1 per second! Yes, we observed that meteor storm for about 4 hrs. I took some video but I have yet to digitize it.

Nice meteor videos, BTW. Your reduction of the data and comparison with the IMO curves is very impressive!

Cheers.

4. dorigo - August 16, 2007

Hi Changcho,

I know mount Hamilton, what a wonderful place… I had the pleasure to look through the large refractor a couple of times. One meteor per second, wow! Try to work at your video if you can…

The analysis of the three hours of footage took me a long time – it was not easy to find the right limiting magnitude of the video frames (and indeed it is not even a very meaningful quantity since the ccd has a sensitivity vs frequency curve different from that of the human eye)… I am quite satisfied of the result. My visual observations that night were instead written in a sheet of paper I lost!

Cheers,
T.


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