(meteorobs) Re: IMO Shower Circ.: 2nd Perseid profile

[Marco Langbroek]

> As to the weakness in video records: Concerning European
> video data, the peak may be screened by the low radiant
> in the beginning of the night. As the radiant
> moves up quickly, dropping rates may be compensated by
> geometric number increase. The peak wasn't prominent in
> western-European visual observers' impressions either.

Hi Rainer,

Yes, and in addiution of thhe increasng radinat altitude matcing the
downdrop, I think this peak "drowned" in the combination of low radiant
altitude and twilight limiting magnitudes (and hence large variations in
calculated ZHR due to large correction factors) in northwest Europe. I can
barely see a hint of it in our Dutch data. Too bad. But even the group in
Roumania, where the radiant was higher, did not quite experience a "peak"
feeling. Looking at your preliminary IMO results, it was all quite stretched
and shallow, maybe that's the answer.

For me (and others!), the big surprise of this night still was the unusual
number of bright Perseids over a prolonged period after the predicted peak.
In fact, the impression is that this only started after this peak, although
again the effect of low radiant in the start of the observing run might
partially account for that.

- Marco

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Marco Langbroek
Dutch Meteor Society (DMS)
Leiden, the Netherlands
52.15896 N, 4.48884 E (WGS 84)

e-mail: meteorites at dmsweb.org
DMS website: http://www.dmsweb.org
priv. website: http://home.wanadoo.nl/marco.langbroek
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