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(meteorobs) No outburst from Ursids in 2001?
Because the Dec 2001 is close to the dividing line of two resonant windows,
no Ursids outburst has been expected to happen now.
We made however some check-modeling. Most of the computer work and searching
of possible encounters was made by Markku.
Actually an encounter with a trailet from 1392 was found. The encounter is
at about rD-rE=0.001au, which is a relative close encounter, considering the
trail age. It appears however that the trailet has near the encounter, the
very small mean anomaly factor (fM) of about 0.0002. A comparison with the
2000 encouter is difficult because of quite different local properties of
the two trailets.
We expect that because of the very small fM, there will probably be no
observable outburst. The rates from this trail are expected to be (maybe
well) below the yearly background.
We give the solar longitude (2000.0) of the encounter as 270.919. The
corresponding time is (tomorrow) Dec, 22, at about 17:30UT.
We are seeking for possible encounters in 2002. There seem to be quite a lot
of resonant meteoroids passing by in Dec 2002, ejected during a few comet
returns around 1100 AD. However, for the most part these particles pass
inside the Earth orbit, (even though the parent comet orbit is well
outside). We have found and selected a few trails for more detailed
inspection and modeling. We will come to this later. We were now in a hurry
to study the possible 2001 encouters.
Esko Lyytinen
esko.lyytinen@minedu.fi
esko.lyytinen@www.fi
Markku Nissinen
markku.nissinen@pp.inet.fi
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