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(meteorobs) BACKGROUND: Meteors from Schwassmann-Wachmann 3




Meteors from Comet Schwassmann-Wachmann 3 -- background
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(full story: see LUTHEN, ARLT, JAGER: WGN - Journal of
the IMO 29:1/2, pp. 15-28.)

Dust trail computations of particle sets ejected at
various perihelion passages of the Comet were carried
out by HARTWIG LUTHEN, Hamburg, Germany. The evolution of 
these dust trails is studied for ejection years back to 
the 1890 perihelion passage. Close approaches were found
for the 1908 dust trail in 1936 and the 1995 dust trail in
2022 with farther approaches in 1984, 2001, 2011, and 2017.

The orbit of P/Schwassmann-Wachmann 3 was integrated back
to 1890, using the orbit from the JPL database, allowing
for the gravitational effects of all nine planets and for the
non-gravitational terms A1 and A2. Extending the computation 
further backwards was not attempted. Slight variation of the 
initial orbit resulted in massive changes in the times of 
perihelion passage when integrated to back to the pre-1890 
years, indicating that the accuracy of the initial orbit does 
not warrant such an attempt. Then orbits of test particles 
having the orbital elements of the comet at perihelion, but 
different semimajor axis were generated, and integrated to 
the  present time (using the gravitational effects of the 
major planets except  Pluto). This approach is similar to 
that of MCNAUGHT & ASHER for the Leonids.

The Table shows a compilation of the Earth's passages close to 
SW-3 dust trails found in this study. The rates of all these 
displays are hard to predict, since there is no reliable prev-
ious observation helping to establish any idea of the particle 
distribution as a function of Delta a_0 (the deviation of the 
particles semi-major axis from the Comet's one). Since all the
displays occur at negative Delta a_0, on orbits which radiation
pressure cannot assist particles to achieve, we feel that the rates
would not be too high. This is especially true for the 2001,
2011 and 2017 events. However it appears possible that
careful observation may establish some activity at the times
of the predicted maxima. We are a bit more hopeful for the
2022 event, since the miss distance r_D-r_E is much smaller,
and the chance is that the trail is more populated due to
the massive expulsion of dust observed in 1995.


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Overview of six close encounters with dust trails ejected from
Comet 73P/Schwassmann-Wachmann 3. The geocentric velocity V_g 
(given in km/s) needs to be increased by the about 4 km/s for 
observing purposes due to the gravity of the Earth.


Date of enc.   Trail Delta_a0 rD-rE  Node  alpha delta  V_g 
                                    (2000)
1936 June 7.78  1908 +0.051  0.0003 77.69  221.5 +44.7  13.9
1984 June 3.47  1952 -0.052  0.0023 77.28  219.3 +36.8  13.2
2001 May 30.41  1941 -0.027  0.0026 69.04  212.2 +28.4  12.5
2011 June 2.24  1952 -0.022  0.0011 71.22  214.2 +33.5  12.9
2017 May 31.136 1941 -0.012  0.0013 69.64  212.6 +29.7  12.4
2022 May 31.205 1995 -0.022  0.0004 69.44  205.4 +29.2  12.1
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(comp. Rainer Arlt)

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