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(meteorobs) Outburst Nov 1/2, 2/3 from comet 103P/hartley2?


I recently received a Newsletter from the California Bay Meteor Society of
which Peter Jenniskens is highly involved with. In it, the prospects for a
meteor outburst from comet 103P/hartley2 is discussed. Below is pieced
together quotes from the newsletter in regards to it by Peter and others. It
may be a good idea to observe if able on these two nights.
George Zay
----------------------
ON THE PROSPECT FOR A METEOR OUTBURST FROM COMET 103P/HARTLEY2

On Saturday evening, Nov 1/2, there is a chance that meteoroids of comet
103P/Hartley 2 cause a meteor outburst visible from California. This is a
short period comet that has recently been perturbed into an orbit just inside
to just outside the earth's orbit. 

On November 3, 1997, the earth will pass close to the orbit of comet
103P/Hartley 2. At 00.9 h UT, the minimum distance will be +0.040 AU and the
earth will lead the comet in passing that point by only -49.0 days. The comet
orbit has just moved from just within to just outside of the earth's orbit.
That is a signal that some unusual meteor activity may occur. The meteors
should radiate from beta-Cygni and enter at a slow 17 km/s entry velocity.
Without knowledge of the dust environment of this comet, we can not be
certain about the time of the eent (we pass the comet node already on Nov. 2
at 07.1 h UT) nor the magnitude of the event (calculations of dust ejection
show that the earth will pass somewhat in front of the main dust sheet). No
past meteor outbursts are known from 103 P/Hartley2. However, other such
comets have given displays as good as a Perseid return in summer under
somewhat similar encounter conditions.

The earth will pass closest to the comet's orbit near perihelion rather than
at the comet's descending node on Nov.3 at 0.9 hours UT (solar longitude
220.681-J2000). "If there is a shower, this would be the time of shower
maximum", according to Yeomans. Conditions are excellent, with only a sliver
of a moon early in the evening. Yeomans calculated an apparent radiant
position at approximately RA = 295.6, DEC=+31.3 degrees, not far from
beta-Cygnus. That is quite a bit higher in declination than a previous
radiant calculated by Hasegaw for the 1985 orbit: RA=290, DEC=+7. That is
good, because it extends the period that the stream radiant is above the
horizon for northern hemisphere locations.

What are the chances that there will be a meteor storm? Yeomans calculated
that the earth will lead the comet to this close approach point by 49 days.
That is very little. But the separation distance will be some 0.40 AU with
the earth just outside the comet's orbit, which is very large.

Moreover, calculations by Mark Matney show that the most recent dust may not
have spread far enough along the comet orbit for earth to be able to meet it
49days in front of the comet. This is not a certain conclusion. However, it
is clear that we should not put our expectations too high. 

If an outburst occurs at 0.9 hours UT on Nov. 3rd, as predicted by Yeomans,
then the outburst can be seen in the early evening of November 2nd by
observers on the east coast, while west coast observers may be able to see a
tail of it. For observers in north western parts of Europe, the outburst is
expected to peak shortly after midnight. Best viewing is over the Atlantic
Ocean.

Thus, World-wide monitoring of meteor activity is needed on the nights of
November 1/2 and 2/3 to increase the chances that the event will be observed.