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Re: (meteorobs) Re: Leo 2001 coverage in S&T 3/2002
> Lower counts can't set a minimum on the ZHR. The fact that
> Observer B might have perceived only 500 Leonids during the
> same hour from the same location must be considered, but it
> still seems to me that the higher actual count must set a
> minimum constraint on the actual ZHR.
the ZHR is a representative measure of meteor activiy and
says how much an average, single observer sees in an hour,
radiant in the zenith, lm=6.5. the individual zhrs can have
significant scatter, values in the range 30% to 300% are
typical in any set of individual zhrs at the same time.
experienced observers are often mixed with high-perception
observers. the best observer is not the one who sees most
meteors.
with the leonids we have a special situation. usually
people see 98 % of their meteors in a 100-deg field. the
high alert during a storm may widen this field considerably.
some 10-20 degrees more mean a lot more of atmospheric volume
even though the perception at the edge is low.
i prefer to have, at various locations, samples of very
different types of observers. their averages give good
representations of the activity. the selection of a group
is most dangerous. i am sometimes getting tired of
'experienced' observers in the analysis... what we need
is not the best rates, but something COMPARABLE to all
other situations like a simple Perseid night. from comparison
with other observations during the leonids, i judge that
the high-alert observations will certainly not be comparable
with a perseid maximum of the same people under same
conditions. so what does a ZHR then mean? that makes the
thing tricky, and i prefer to rely on an average of a very
heterogeneous set of data even if one groups sees doubled ZHR.
best wishes,
rainer
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