1. SPA Meteor Section Preliminary Results: Perseids over the UK and
elsewhere
From: Alastair McBeath
SPA Meteor Section Preliminary Results: Perseids over the UK and
elsewhere
The 2000 British summer, though significantly cooler and wetter in many
parts than for some years, produced some better skies right on cue for
the Perseids. Indeed in SPA Meteor Section data already received, only 5
of the 24 nights from July 19-20 to August 11-12 inclusive have so far
produced no visual meteor reports, a situation virtually unique for at
least the past 17 years!
UK watchers to submit observations to date (in England unless noted)
include: Mary Cook (Avon), Maggie Daly (Middlesex), Shelagh Godwin
(Surrey), Philip Heppenstall (West Yorkshire), Jeff Lashley (Fife,
Scotland; video data), Tony Markham (Staffordshire), Alastair McBeath
(Northumberland), Trevor Pendleton (Lincolnshire) and George Spalding
(Oxfordshire). From overseas, we have detailed results from Zoltan
Hevesi at Kaposvar, Hungary, provisional reports from two "Astroclub
Canopus" observing camps at Avren and Kamen Bryag, Bulgaria (via
observer and co-organizer Eva Bojurova), similarly brief reports from
part of the German "Arbeitskreis Meteore" team (Rainer Arlt, Sirko Molau
and Oliver Wusk) who were at Ketzuer in Germany, as well as some initial
impressions from Bob Lunsford in California, USA, even before he´d been
able to review his meteor-count audio tapes!
Observed Perseid numbers were high enough to compute reliable ZHRs by
July 26-27 (ZHRs ~6-7 +/- 4-5 from July 26-27 to August 1-2), although
the first swift-flying Perseid meteors were noted in even casual
sky-checks from about a week before this, much as normal. Shower ZHRs
were just into double figures by August 3-4, averaging 12 +/- 5 from
then until August 8-9, though rates were beginning to pick up by this
latter date. On August 9-10 and 10-11 (mean ZHRs 23 +/- 6 and 33 +/- 7
respectively) some signs of rates increasing slightly overnight were
seen. These signs were clearest on August 11-12 when the average ZHR was
73 +/- 10, and values rose overnight from ~55 to ~85, after dusk to near
dawn. The ZHRs from August 9-10 to 11-12 especially, suffered problems
because of increasingly strong moonlight, which persisted until almost
the start of morning twilight from Britain by August 11-12. As a result,
the ZHRs on this latter night particularly may be a little too high,
although encouragingly they are in-line with the preliminary IMO values
in the "Perseid Shower Circular" issued on August 16th. The Perseid
maxima occurred during daylight for the British Isles on August 12, so
were not recorded by our watchers, and naturally all the ZHRs quoted
here are subject to revision as further reports arrive.
UK correspondence to date shows much of England enjoyed a good night on
August 11-12 in spite of the Moon, with only thin, typically hazy,
cirrus clouds reported, though these were quite widespread. Limiting
magnitudes with the Moon still up were around +4.9 to +5.3 at best, but
a few people were lucky in getting a +5.5 sky briefly between moonset
and morning twilight. As often happens near Perseid maximum, several
watchers were tempted into continuing their observing into too-strong
twilight, still spotting occasional bright Perseids until just an hour
before sunrise in one case.
English observers seemed generally pleased with their night´s work on
August 11-12, though as Rainer Arlt in Germany also noted, a little
clearer sky would have been even better. Perseid rates were good without
being spectacular, as veteran George Spalding commented, echoing the
thoughts of other experienced meteor watchers, which suggested the best
was still to come after dawn over Europe. Plenty of bright Perseids
(magnitude +2 or brighter) were seen, but fireball gems were rare, the
brightest so far a magnitude -6 blue-green-violet event at 00h37m UT on
August 12, which produced two flares and a 13-second long persistent
train.
In North America, where some of the highest Perseid rates were seen this
year, Bob Lunsford remarked that the impressive meteor display was
scarcely dimmed by a layer of smoke over his usually excellent
Californian sky, the smoke due to the horrendous, extensive, forest
fires all across the western USA, still burning at present. Thankfully,
there seem to have been no casualties among our North American meteor
observing colleagues because of these fires as yet. Bob also mentioned
the smoke layer concealed any sign of the auroral activity spotted from
numerous other sites in North America coincident with the Perseids´
best.
Eva Bojurova reported the Bulgarian "Astroclub Canopus" watchers had a
very successful observing camp at Avren from July 24th to August 5th,
mainly concentrating on the various Aquarid-Capricornid showers. They
then returned to Kamen Bryag on the Black Sea coast to celebrate the
first anniversary of the total solar eclipse beautifully witnessed from
there on 1999 August 11. Their 2000 Perseid peak observing was less
fortunate, as overcast skies appeared nicely in time for moonset on
August 11-12!
Many thanks to all the observers who made contact so swiftly by e- and
ordinary mail, allowing this first SPAMS overview to be issued just a
week after the Perseid maxima. I look forward to seeing the data still
to come however - all further meteor observations will be gratefully
welcomed, as always. Clear skies for your next watches!
Alastair McBeath,
SPA Meteor Section Director.
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