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Re: (meteorobs) A-T 1996 ZAYGE ...long article
George,
Thanks for the analysis on your observations of the A-T radiant. I need
more time to reread this, but I do have some initial comments.
First, remember that the majority of the meteors seen by Gliba and myself
were short-trailed, so our velocity estimates will seem slower than when at
the distances you were observing at.
Second, it seems you are trying too hard to justify the nonexistence of the
A-T's, without considering the observations by others. There are others who
plotted meteors this year and reported weak activity from the A-T region,
especially from around Alpha Triangulii. Considering everyone would have
seen different groups of meteors, the concept of "chance alignments" does
not seem to really apply. The same is also true of the observations by
George Gliba and myself in 1993, as well as the observations in 1994. The
historical data shows three other instances where A-T radiants were
detected independently by two other people (one time they were separated by
the Atlantic Ocean), so, once again, we have two people seeing totally
different meteors and identifying a radiant within the A-T range. I do
agree with you that the A-T's may be periodic, because it is interesting
that the four cases of this activity being independently discovered could
be represented by an orbital period of about 5.5 to 6 years. Certainly a
nice number to indicate the parent might have been a comet from Jupiter's
family.
Finally, in your conclusion, you said, "since the intial announcement was
based on visual observations, I highly doubt that a telescopic shower can
be associated with the initial observations..." This is very incorrect. All
meteor streams will be composed of various sizes of particles. Photographic
streams will always have visual and radio counterparts, and visual streams
will always have radio counterparts. This is the nature of stream formation
from comets. You will never have particles that will only be large enough
for visual observations within a stream. In fact, many radio surveys
indicate the small, radio meteors are more numerous than the visual ones,
for every stream studied. Thus, a telescopic stream being active at the
same time as the visual A-T's is very probable!
I think the main problem is there is no standard procedure for the study of
minor meteor streams. There have been astronomers who have noted (some up
to 30 years ago) that a study of minor streams might be valuable in the
study of the evolution of meteor streams, and maybe even comets, with the
latter being added after the discovery of minor planet 3200 Phaethon
orbiting within the Geminid stream orbit. Unfortunately some amateur
organizations prefer to completely ignore minor meteor streams. This is a
shame since proper procedures could enable such studies to be productive,
and, once again, amateur astronomers could make a major contribution to the
field.
Personally, I also have some problems with the A-T stream. The main problem
is that an orbital period of 5.5 to 6 years is indicated by the best
observations, which indicates a Jupiter-family comet, but the inclination
is way to high. Such an inclination is not easily explained by models of
the orbital development of Jupiter-family comets. This problem may or may
not be resolved by continued observations of this stream.
Another of my problems is the duration indicated when considering all of
the historical observations. A duration of 10 or more days is not typical
of high-inclination streams. My personal gut feeling is that the stream has
a rather short duration of only a few days, which would also indicate a
rapid falling off of visually observed numbers of meteors the further you
get from maximum. Fortunately all of the independently discovered radiants
fall within a narrow range, so these would not be excluded.
Sincerely,
Gary
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