Leonids 2011

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Alastair McBeath
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Leonids 2011

Post by Alastair McBeath »

It's possible there may be strong Leonid activity this year, Zenithal Hourly Rates (ZHRs) perhaps reaching ~200, around 22:36 UT on November 16-17. Unfortunately, the dust particles involved are expected to be very small, and are thus unlikely to produce many readily-visible meteors. The event could be detected by radar or sensitive amateur radio meteor equipment despite this. However, the timing will be poor for Britain, as the radiant, in Leo's sickle-shaped "Head" asterism a little way northwest of the temporary Mars-Regulus line, rises here at about 23h UT, and can be usefully-observed only after midnight.

Other Leonid maxima may occur this time as well, on either of the following two nights. For November 17-18 the potential timings are around 21h UT (ZHRs maybe 20) and near 03:30 (ZHRs ~10-15?), and circa 23h UT on November 18-19 (ZHRs ~20 perhaps, but probably again of faint meteors, if anything happens at all).

Unhelpfully, the Moon is at last quarter on November 18, so will be bright, waning gibbous and well on-view throughout the time the radiant is observable on the three key nights. The chance of multiple maxima of variable strength means checking anyway will be important to try to establish whatever takes place, Moon or not. Additional peaks are not excluded by these predictions of course, nor are there any guarantees these peaks will definitely happen as anticipated!

For best effect near the maxima, view as much clearer sky as you can comfortably, watching away from the Moon or any surfaces reflecting moonlight, and not too close to the Leonid radiant (partly because the Moon is to the northwest between November 16 to 18, but mainly as shower meteor trails are much shorter nearer the radiant, and thus harder to see). This advice applies as well for anyone hoping to try some Leonid imaging. Leonids are very swift meteors, and often leave fine persistent trains.
Good luck, and clear skies!

Alastair McBeath,
Meteor Director, Society for Popular Astronomy.
E-mail: <meteor@popastro.com> (messages under 150 kB in size only, please)
PaulB
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Post by PaulB »

Dear Alastair,

Thank you for pointing this out. I am listening to a live feed from the US. So I hope to be able to pick UP activety from the shower, after midnight.

If anybody is interested here is the link.

http://spaceweatherradio.com/index.php
Paul Anthony Brierley
Observation Co-ordinator for.
Macclesfield Astronomical Society
https://www.flickr.com/photos/paulabrierley/
http://pabastronomy.blogspot.co.uk/2018/
Alastair McBeath
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Joined: Sat Jul 23, 2005 6:51 pm
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Post by Alastair McBeath »

I'm sure it will astound no-one to discover conditions seem to have been generally poor across the UK yet again, for the Leonids. I had a few "clearer" spells towards dawn on Nov 16-17 here in NE England, but with variable mist/fog and the Moon, the limiting magnitude was about +3, so impractical for proper meteor observing. I didn't spot any meteors in various sky-checks, lasting maybe twenty minutes overall!

Conditions elsewhere don't seem to have been ideal either judging by the lack of data sent in to the International Meteor Organization (IMO) so far. If you'd like to see what has been reported, check their "live" visual results page at:

http://www.imo.net/live/leonids2011/ .

Any data from Britain, or indeed elsewhere in the world, would be most welcome still!

Alastair McBeath,
Meteor Director, Society for Popular Astronomy.
E-mail: <meteor@popastro.com> (messages under 150 kB in size only, please)
adrian lord
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Post by adrian lord »

I have been out observing the last few nights with my scopes as the weather here has been so good, and, incidentally, I've seen a lot of meteors, small fleeting dust types, as predicted.
TMB/APM 152 apochromatic Refractor is my weapon of choice!
Alastair McBeath
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Re: Leonids 2011

Post by Alastair McBeath »

With the potential for four Leonid maxima in 2011 scattered across November 16 to 18 inclusive, one of which might have produced activity in the low hundreds, albeit all with a problematically bright waning Moon, it was disappointing that weather conditions for SPA watchers globally seemed to have been unusually poor. Even visual reports to the IMO's online data page for the shower were unhelpfully thin on the ground, with just four datapoints available between ~18h UT on November 14 through to ~00:30 UT on the 20th. At least for once, it wasn't just Britain's weather at fault!

These IMO results suggested merely a single Leonid peak had happened, on November 17-18, when ZHRs reached 22 ± 3. Huge gaps in the data meant this result was especially tentative however, and it would have been very easy for any short-lived outburst, no matter how strong, to have passed entirely unseen. IMO video observations proved less helpful too than might have been hoped (presented in "WGN", 40:1 for 2012 February, on pages 48-52, especially p. 49), where only a single combined datapoint was determined for each night, based largely on European results. They indicated a single peak on November 18-19, apparently with activity still quite good by the following night. Again though, the broad timescale meant large breaks between these reports.

Looking to the radio meteor results collected by the SPA, even these gave incomplete coverage, since with observers based primarily in central-western Europe and western North America, the Leonid radiant was effectively unobservable, because of being below the horizon for all locations, from about 20h-21h until 00h-01h UT daily, a period into which fell three of the four predicted maximum timings. To hunt for what the data did show, a detailed hour-by-hour examination was made of the radio information available from November 16 to 20, concentrating on when the Leonid radiant was observable from each site. No distinct brief maxima were found on any of these dates, but activity probably due to the Leonids seemed to have been somewhat stronger than normal on November 17, between roughly 02h-13h UT, and was at its strongest on November 19 from about 01h-14h UT. (Remembering that these intervals do not show true peaks, but indicate instead the better-detectable daily period for radio Leonid meteors from the two main geographic regions represented.)

Overall, this radio meteor pattern supported the findings of the IMO video observers much better than those from the visual reports, and implied the better shower activity could have occurred on November 18-19, significantly later than any of the advance predictions had anticipated. In all cases, shower rates were apparently fairly unremarkable, which would in turn infer quite typical Leonid ZHRs had taken place, probably of the order of 15-20 or so at best, much as the visual data found. Any further results from elsewhere would be welcomed still to try to plug the gaps and see if anything unusual did happen in time to any of the late-evening-UT peak predictions.

The list of contributing observers to the Meteor Section from across the Leonid epoch were as follows, including reports sent in directly, posted on the Leonids topic of the UK Weather World's Space Weather Forum, at:

http://www.ukweatherworld.co.uk/forum/i ... nids-2011/ ,

or forwarded from the Arbeitskreis Meteore group in Germany (via their journal "Meteoros" 15:1, 2012 January, and 15:2, 2012 February, thoughtfully provided by Ina Rendtel; see http://www.meteoros.de ), from the North American Meteor Network by Rich Taibi (see http://www.namnmeteors.org ), from 2011 December's "The Astronomer" magazine via Tony Markham (see http://www.theastronomer.org ) and from Radio Meteor Observation Bulletins 220 & 221 for 2011 November and December respectively, thanks to editor Chris Steyaert (see http://www.rmob.org ). In the list, "R" means radio observations were provided and "Vi" video or other imaging. Where not stated, visual data only were received.

Orlando Benitez (Canary Islands; R), Mike Boschat (Nova Scotia, Canada; R), Jeff Brower (British Columbia, Canada; R), Willy Camps (Belgium; R), Johann Coussens (Belgium; R), Gaspard De Wilde (Belgium; R), Franky Dubois (Belgium; R), Karl-Heinz Gansel (Germany; R), Christoph Gerber (Germany), Luc Gobin (Belgium; R), Nick James (England; Vi), Glyn Jones (England), Sam Jowett (England), Peter Knol (Netherlands; R), Paul Martsching (Iowa, USA), Peter Meadows (England; Vi), Sven Näther (Germany), Mike Otte (Illinois, USA; R), Jürgen Rendtel (Canary Islands & Germany), Steve Roush (Arizona, USA; R), Wayne Sanders (British Columbia, Canada; R), Andy Smith (England; R), Chris Steyaert (Belgium; R), Mikhail Svoiski (Arizona, USA; R), Rich Taibi (Maryland, USA), Istvan Tepliczky (Hungary; R), Felix Verbelen (Belgium; R).

Fulsome thanks are due to one and all during such a very difficult Leonid spell for observers, both for data and comments on the shower.

Alastair McBeath,
Assistant Meteor Director, Society for Popular Astronomy.
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