Society for Popular Astronomy

[Alastair McBeath]

The main Orionid maximum is due a week today, on October 21, when the radiant is near Orion's "Club" asterism, an area of sky usefully observable for meteor work from about 23h UT onwards. An International Meteor Organization (IMO) analysis some years ago suggested Orionid Zenithal Hourly Rates (ZHRs) could be around 30 at best this year, at their latest, possibly cyclical, activity peak, between roughly 2008-2010. In 2006 to 2008, abnormally strong Orionid returns occurred, with ZHRs of 40-70 on two or three consecutive dates across the predicted peak. Another IMO analysis after the 2006 event indicated no good likelihood for similarly protracted, enhanced rates to still happen this year, so it will be interesting to discover what does transpire. Even in a normal year, the build-up to and fall-away from the Orionid maximum tends to be fairly gentle, with ZHRs of ~15 or more persisting from approximately October 18-23. In addition, a sub-peak, with ZHRs comparable to the normal main maximum, has happened in the past on October 17-18, though definitely reported from only two years so far, 1993 and 1998. With new Moon on October 18, conditions could scarcely be more perfect for covering whatever near-maximum Orionid activity comes-by this time.

For more information and an Orionid radiant chart, see the October meteor activity webpage at:

http://www.popastro.com/sections/meteor/meteor-oct2009.htm .

Good luck, and clear skies!

Alastair McBeath,
Meteor Director, Society for Popular Astronomy.
Meteor homepage: http://www.popastro.com/sections/meteor.htm
E-mail: <meteor@popastro.com> (messages under 150 kB in size only, please)

[cosmic dave]

I am going to give it a go this year. got my recliner deck chair ready, now lets hope for some clear sky
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The world is a wonderful place if only we stop and look. Skywatcher evostar 90 refractor/ celestron 15 x 70 binoculars

[Kevin Brown]

Alastair,

My local astro soc at Cranbrook, Kent is taking the early watch. We have a public meteorwatch on Monday October 19th.

I'll let you know, what we see..

Kevin
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Kevin Brown, SPA webmaster
My astro blogs.. iya2009.com | Practical Astronomy magazine

[Alastair McBeath]

The overnight weather after midnight BST has been pretty poor here in Northumberland on the past few nights, so I hope you have better luck Dave and Kevin.

Kevin, your posting suggests an evening meteor observing session, perhaps with quite a few first-time meteor watchers. It is important for anyone taking part to appreciate in advance that meteor rates are at their daily lowest at this time, and that no Orionids will be visible until much later on in the night. Useful Orionid observing (i.e. where you can realistically hope to see more than the odd Orionid meteor per hour) is only practical after midnight BST. Meteor rates generally are at their daily best in the hours leading up to dawn (the daily sporadic peak is around 06h UT for Britain) - unfortunate, but true!

Alastair McBeath,
Meteor Director, Society for Popular Astronomy.
Meteor homepage: http://www.popastro.com/sections/meteor.htm
E-mail: <meteor@popastro.com> (messages under 150 kB in size only, please)

[Kevin Brown]

Alastair,

Thank you for the detailed information.

Yes it is an early evening (8pm start) session. A short meteor talk is planned if there's cloud, or the little blighters just don't show up!

I'll report back..

Cheers
Kevin
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Kevin Brown, SPA webmaster
My astro blogs.. iya2009.com | Practical Astronomy magazine

[DarkerSky]

For the UK there is a complex area of low pressure moving in from the Atlantic through this week, so observing conditions could be tricky due to cloudy skies and rain.

At the moment (Sun 18th) these look like the best areas for observing Orionids in UK

For 19th/20th the East coast of England and Scotland looks the best bet for some clear skies ahead of the advancing weather front

For 20th/21st Ireland, Wales and SW England could have some crystal clear skies behind the cold front - esp later on into dawn

For 21st/22nd - The sky will clear from the South/Southwest across much of Wales and Central / Southern England as rain moves north through the night. Could be some beautiful skies behind towards dawn (low confidence)

All subject to change - as always with the British weather. I'm going to give it a go this year if the cloud breaks enough

[Alastair McBeath]

Sorry to see no postive postings here yet, though I'm not surprised. Last night (Oct 20-21) was a complete, literal, washout here in Northumberland, with solid overcast and rain. Daylight (if you can call very heavy overcast that...) today yielded no improvement, but we'll see what the post-midnight period brings for tonight.

I was able to get out for a couple of short watches on Saturday night most recently (Oct 17-18), and saw a few Orionids towards dawn (four in forty minutes after 04:25 UT, plus four sporadics), though conditions were rather variable overnight then, with haze and mist on and off, plus occasional cloud. The limiting magnitude averaged just +5.4 in that late forty-minute session, for instance. No better skies to check since though.

Clear(er) skies to all for the next few nights!

Alastair McBeath,
Meteor Director, Society for Popular Astronomy.
Meteor homepage: http://www.popastro.com/sections/meteor.htm
E-mail: <meteor@popastro.com> (messages under 150 kB in size only, please)

[Kevin Brown]

We had a fantastically clear sky over Cranbrook on Monday night (surprising, because it was murk until 6pm).

The school students claimed quite a few meteors and everyone enjoyed wonderful views of Jupiter and moons. However, just like Alastair advised, I didn't see any meteors unfortunately, and it's been cloudy and wet since.

Still hoping.
Kevin
_________________
Kevin Brown, SPA webmaster
My astro blogs.. iya2009.com | Practical Astronomy magazine

[Alastair McBeath]

Good to know someone had had some decent skies Kevin, even if not at a time for Orionid watching! Glad the evening watch went well all the same; so often, these events are wrecked by the weather, as you know.

Speaking of which... Conditions have continued to be dire here, and elsewhere judging by the comments and lack of hard data from British sites so far.

There was a belated warning from the IAU about possibly enhanced Orionid rates again this year, circulated just ahead of the expected peak, and which I heard about too late to post here. There's no sign strongly enhanced activity was seen this year as yet, though the IMO's "live" Orionids page has been suggesting ZHRs of between 30-45 or so from October 19 to 23. These preliminary ZHR values need to be treated with caution, since they're liable to change every time fresh data are input to the system, plus we were expecting peak ZHRs of ~30 this year anyway. However, the impression is this level of activity has persisted for several days, which would not be quite as expected from a "normal" year. It is comparable to what was seen during the unusual 2006-2008 returns though, so this seems to indicate some enhancement of Orionid activity has happened once more.

Those who've tried to check the IMO website recently may have encountered problems in accessing it. It's in the process of being transferred to another web-host to solve these, but the "live" Orionids page can be found on the still-functional mirror-site from Armagh Observatory, at:

http://www.arm.ac.uk/~gba/imo/orionids2009/ .

Anyone who did manage some Orionid observing from the UK (or elsewhere) and who hasn't sent me a copy of their results yet, please do so as soon as possible! And do keep watching if skies allow, since it's possible activity could remain above normal levels (though probably below the peak rates) for another few mornings yet, judging by the recent past. Even if it doesn't, it's important to know just what did occur!

Alastair McBeath,
Meteor Director, Society for Popular Astronomy.
Meteor homepage: http://www.popastro.com/sections/meteor.htm
E-mail: <meteor@popastro.com> (messages under 150 kB in size only, please)

[david entwistle]

[Alastair McBeath]

I managed one more watch for the Orionids since I last checked-in here, a single hour beginning just after midnight UT on October 25-26. The three Orionids I saw were half the observed sporadic rate then, not too surprising with the radiant still fairly low, and the shower past its best. The LM averaged +5.6 over the hour, with occasional clouds flitting rapidly through in the remnants of the weekend's gales. Unfortunately, it started clouding-up as the watch was ending, and it was completely overcast within 90 minutes of my finishing. All other nights across the expected peak were stubbornly cloudy, often with yet more rain.

On October 22, the IAU claimed unusually high rates of bright meteors had been seen from the shower already on October 20. However, this seemed to have been based on just one observer's data. As I already mentioned here, the "live" IMO ZHRs indicated quite good Orionid activity had persisted for several days across the expected peak, and somewhat variable ZHRs of ~30-45 have continued to feature in those results since, now lasting between October 19-20 to 23-24. Similar ZHR values have been apparent in the more limited visual information reaching me directly, mostly from overseas courtesy of Mark Davis, leader of the North American Meteor Network group. The SPA magnitude distributions (based on currently just over 450 Orionids and 220 sporadics) seem to have been perfectly normal from both sources across the shower's peak, with no unexpected excess of bright Orionids at all. The fact ZHRs were about to somewhat above what was predicted for several days tends to confirm another enhanced Orionid return occurred, since ordinarily, we'd have expected the highest activity to last no more than a day or so.

As David Entwistle's October 25 posting suggested, the radio meteor data have so far shown a quite clear Orionid "bulge" for a week or so. From past years, this has tended to indicate above average, but not outstanding, shower activity. The higher radio counts may have fallen on October 22, but this is only a preliminary estimate. It remains unclear how significant Steve Roush's October 17 minor peak may have been, as it is still unconfirmed by any other radio information to arrive as yet.

I'd hope to give another update on how the shower behaved here in a couple of weeks or so, so all further results would be gratefully received before then. Meanwhile, many thanks to everyone who has provided results of whatever kind from the shower to date.

Alastair McBeath,
Meteor Director, Society for Popular Astronomy.
Meteor homepage: http://www.popastro.com/sections/meteor.htm
E-mail: <meteor@popastro.com> (messages under 150 kB in size only, please)

[Alastair McBeath]

Assistant Meteor Director David Entwistle and I have examined various aspects of the Orionid epoch radio meteor data since my last update here, including those results in Radio Meteor Observation Bulletin 195 for October 2009 (see http://www.rmob.org ). The IMO "live" dataset has also continued to grow, and now shows that average Orionid ZHRs were about 35 throughout October 20, 21 and 22. They then seem to have risen to around 40-45 on October 23, before falling back to ~25 by the 24th, and dropping further thereafter. These values remain preliminary only however, and may change later after a full analysis.

The SPA radio analysis overall, based on from 17 to 21 viable datasets a day (8 from North America and 13 from Europe), showed a reasonably clear peak in echo counts primarily due to the Orionids on October 21, with good activity registered by most operational systems from October 19 to 23 inclusive, tailing off into October 24. There was an indication that modestly increased numbers of brighter meteors (assumed to be those echoes that produced longer than normal radio reflections) were present from October 21-24 inclusive, and that similar events may have been occurring, probably at a somewhat lower rate, from October 19. A loose "peak" in such longer echoes was suggested as lasting across both October 22 and 23. There seemed little evidence for a specific time-dependency beyond the "day" level in all this, as most systems registered generally increased meteor counts whenever the Orionid radiant was clear of the horizon on the dates above. As always, some caution needs to be exercised when considering these radio meteor results, because of the considerable difficulties in carrying out the analyses, but this is our best attempt at a detailed examination.

Once again, many thanks go to all contributing observers, and good luck to everyone for the Leonids next week!

Alastair McBeath,
Meteor Director, Society for Popular Astronomy.
Meteor homepage: http://www.popastro.com/sections/meteor.htm
E-mail: <meteor@popastro.com> (messages under 150 kB in size only, please)