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Re: (meteorobs) Observations 21-28/08/2003
Hi Jan and all,
Thanks for bringing the PER-AUR problem up. It is indeed quite
difficult to distinguish the two radiants unless a specially
chosen field of view is watched. We may even expect quite a
few meteors from the apex region mixing up with the shower
meteors
This is actually the reason why the activity periods were chosen
to end on Aug 25 for the Perseids and to start on that date for
the Aurigids. Note at this point, that activity periods are no
physical boundaries for meteor showers. Meteoroids can in fact
drift unlimitedly far from their parent body's orbit with time.
So there is no real limit for shower acitivity. A lonely meteor
appearing in September may actually be caused by a particle
ejected from Comet Swift-Tuttle, the parent object of the Perseids.
The limits given are thus limits for visual purposes and applicability.
Before Aug 25 it is more likely to see a PER, after Aug 25 it
is more likely to see an AUR. That's why we recommend to concentrate
on one of the two in either period.
Determining the boundaries of activity periods from visual
observations adds very little to the knwledge of meteor showers.
I am not saying there are no Perseids after Aug 25. Well, what to do?
If the field was so unconvenient for shower association, we have
to admit that the observation cannot help in studying PER and AUR.
In the end we are contributing to a scientific research. In this
case I think we could classify the number of AUR+PER as "diverse".
Then we still have a fairly clear sporadic rate estimate which
will be helpful in analyses, provided it can be excluded that the
meteors are simply apex sporadics.
Best wishes,
Rainer
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