(meteorobs) Is there "the" ZHR profile of the Perseids?

[Geert Barentsen]

Hi Daniel,

A "standard" graph of the Perseid ZHR and population index, constructed by
Rainer Arlt and Juergen Rendtel using 20 years of visual data (1988-2008),
is available on page 144 of the new IMO Handbook (
http://www.imo.net/news/handbook ). The 2000-2007 data was also analyzed in
a recent WGN paper ( http://adsabs.harvard.edu/abs/2008JIMO...36...68R ).

These graphs show what you describe.
1) the ZHR drops off more rapidly after the peak (this is hard to see in the
online graphs because the Y axis covers ZHR [0,120+], you'd need to plot ZHR
[0,40] to see it)
2) there is a hint of the lowest population index (i.e. brighter meteors)
occuring just before the maximum.

Judging from the plots on Jeremie Vaubaillon's website, it will not be the
last trail encounter...

Geert



On 19 August 2010 02:58, <dfischer at astro.uni-bonn.de> wrote:

> According to Central Bureau Electronic Telegram #2416 the rather
> pronounced peak of the IMO autogenerated ZHR profile of this year's
> Perseids - http://www.imo.net/live/perseids2010 - around 17:00 UTC on Aug.
> 12 may be due to a (predicted) dust trail produced in 1479: So 2010 would
> then be another year in which the basic ZHR profile from the millennia old
> dust is 'spoiled' by a young individual trail. Same happened last year, of
> course - but how often is this the case? And are there well-observed
> Perseid ZHR profiles in the literature for which we know for sure that
> there were no trails messing around? The automatic 2008 and 2007 profiles
> on the imo website both look 'complicated', too.
>
> This not just an academic question (though an interesting one): It would
> be nice to have a "standard" PER ZHR(t) diagram, if such a thing exists,
> for more precise - if possible - predictions of what to expect in the
> night(s) before and after the peak. There is a widespread belief, for
> example, that the ZHR decays more rapidly after the peak - in the 2007,
> 2008 and 2010 data this is clearly(?) not the case. Another question would
> be whether the fraction of bright PER is higher in the days before the
> peak than on peak night itself (as some claimed this year); this should be
> easy to answer from the data base.
>
> Dan
>
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