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Re: (meteorobs) more on Gamma ursae Majorids of 1999J3 Linear
Hello Joe and others,
There is perhaps a slight miscommunication entering; priority about who
came up first with the possibility of 1999J3 meteor activity was not so
much the concern (at any rate, Reinder's messages about this were spread
among a rather limited public only, and on a larger scale only in Dutch
- a call for attention was published in print in 'Radiant', the journal
of the Dutch Meteor Society, in the October issue which appeared October
2nd -but completely in Dutch, and who reads such obscure language).
Reinder and me distinctly choose not to make it a large scale general call
anyway, given the true extent of the prospects, i.e. the many uncertainties.
The concern was more that Reinder and me felt that indeed, not too much
should be expected from this 'stream' -yet, we thought it wise to keep an
eye open at November 11!- giving us a little bit uneasy feeling when
reading comparisons with the Draconid comet etc. In the case of 1999 J3
we have a distinctly different situation, and no clear examples exist
where a comet of the type of 1999J3 has been responsible for a notable
meteor activity; that is, coupled to a perihelion passage at least..
In other words; there is no precedent suggesting a possibility of
significant activity; and comparisons given that might suggest such a
precedent, are not if you objectively look at them.
The irony of the thing is, that comets of this type can be coupled to 'far
comet type' outbursts (in Jenniskens' terminology, A&A 295 (1995), 206;
and A&A 317 (1997), 953), i.e. outburst that occur when the parent comet
is (far) away and not near perihelion: the alfa Monocerotids coupled to a
(unknown) very long period parent comet, and the Aurigids associated to
1911 Kiess are examples (see P. Jenniskens et al. Astrpoh. J. 479 (1997),
441; and Jenniskens A&A 317 91997), 953). Generally, however, it seems
that the miss-distance between the orbit and earth orbit still has to be
slightly smaller for that than is the case with 1999J3.
At any rate, perhaps some low level activity is possible, but I really do
not expect significant activity. Still, better to keep an eye open!
- Marco Langbroek
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