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(meteorobs) Fwd from GeoZay Re: KAQ and SOR
Hey all!
Just thought you all would like to see the response from Juergen Rendtel
pertaining to the reasons for eliminating the KAQ's and SOR's from IMO's
working list.
George Z.
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>>>George,
Thanks for your note.
When using a method for observations we also need to deal with its
limits. The major disadvantage of ***any single station observation*** is
that we have only a suspected shower association since we do not know
the orbit of the particle we observe. Of course, we can apply a number
of good criteria to reduce the doubt about our association. Another source
of uncertainty is the error of the visual observation itself, concerning
the direction, the apparent trail length, and the angular velocity. It
has been shown that the loss of shower meteors due to errors in these
quantities can be compensated by assuming a larger radiant size than
the size we may obtain from photographic or video observations. In doing
so, we also allow a certain `pollution' of the shower meteor sample by
sporadic meteors.
So what is achievable by visual meteor observations? Obviously, the
main goal is the determination of physical quantities of meteoroid
streams, such as the number density or particle fluxes. In case of major
showers, of course, the above mentioned errors are of lower importance.
Using visual data for the analysis of minor showers soon brings us
to the limits. Experiments as well as simulations show that we may expect
several `radiants' (i.e. points in the sky for which we can find backwards
prolongations of several meteors) every night. Of course, there are more
showers than in the IMO's list of visual showers. I also agree that showers
with very low entry velocities (like the alpha Bootides or perhaps the
kappa Aquarids) can be better distinguished from others than meteors from
a shower with V of the order of 40-50 km/s. But what can we really do with
a ZHR of 0.5 or so? Our magnitude sample remains small and will be contamined
by sporadics, hence the ZHRs are in error due to an uncertain population
index
AND the accidentially included sporadics. I think that the visual
observations
are not suitable for obtaining relevant data about the particle stream.
Consequently, we left these showers out from the IMO's list of visual
showers.
Hope my comments are of some help. Look forward to hearing from you again.
Regards,
Juergen<<<
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