(meteorobs) RE: Lyrids 1-rev. encounter in 2006

Esko Lyytinen esko.lyytinen at jippii.fi
Wed Apr 19 10:18:43 EDT 2006


Hi Mikhail and all,

Yes, the parent comet orbits goes inside the Earth orbit and so is the 
situation (besides the 1-rev. trail) quite probably with the densest 
parft of the stream. This  may not be quite certain since the parent 
comet inner orbit "shifts" a bit at each return by planetary 
perturbations almost randomly inward or outward (I expect) and we may 
not know if it has passed inside the Earh orbit for a very long time. 
This, above is however now the best assumption (that I know) that the 
densest part of the stream passes inside the Earth orbit and now in this 
year like in 2005 it is perturbed by Jupiter (mainly) more close to the 
Earth orbit than on average.
So I agree Mikhail, that the usual maximum also can be more prominent in 
this year.

Esko

 >>
Hello, Esko and all,

Thanks for the info. If I understand correctly, the fact of 1st rev
trail perturbation means that background Lyrids stream is also can
be moved closer to the Earth orbit, like during Perseids 2004. If it
is so, besides possible activity from 1st rev. trail usual Lyrid
maximum can be more prominent this year. In 2005 the situation was
quite similar, but there was unfavorable conditions with moolight.
This year is much better (though not perfect) to check probable
enhancements in Lyrid activity.

Best regards, Mikhail



EL> Hi all,

EL> The 1-rev. Lyrids trail passes quite close to the Earth in 2006, but a
EL> little too far away for a definite outburst. This is about like last 
year.
EL> In 2005 it passed by about 0.0017 AU inside the Earth orbit. Now it 
will
EL> pass at a little bigger distance of 0.0020 Au.

EL> In a private massage Sirko Molau tells that some level peak may have
EL> been present in the (2005) video-observations around the time of
EL> predicted encounter:

EL> " ..when I analysed our 2005 Lyrid video observations I found enhanced
EL> activity
EL> betwen about 00:30 and 2_30 UT on April 22.
EL> (http://groups.yahoo.com/group/imo-news/message/1559)
EL> ... Our result fits quite well, even though its no proof since
EL> interference from the moon and twilight could explain the result as 
well."

EL> The peak time was predicted at 1:30.

EL> In this year the time of encounter is predicted at sol.long 32.031 .
EL> This is April, 22 at 9:25 UT. This can be possibly observed in 
Americas.

EL> Assuming the trail density-decline (outside of trail-center) to be like
EL> in young Leonids trails, a comparison with last year would yiel now
EL> about 60% the (eccess) rates of last year.
EL> The meteors from this trail encounter are expected to be mainly dim. So
EL> under very good conditions and/or sensitive video cameras this increase
EL> may be detecred, maybe not? (The Moon is a little past last quarter, so
EL> makes harm especially for faint meteor observing.)

EL> Encounters other than the 1-rev. trail can not be predicted, because 
the
EL> parent comet motion would need to be known back to the return of 
ejection,
EL> Some level outbursts that were not from the 1-rev. have been mainly
EL> observed when the 1-rev. trail is quite nearby like now. This kind of
EL> outbursts were observed (among others) in 1945 and 1946. This was 60
EL> years ago which means that there are 5 Jupiter orbital periods and 2
EL> Saturn orbital periods in between.
EL> On the other hand if those encounters were for example from 2-rev.
EL> trails, then in the first return of these meteoroids, Jupiter would 
have
EL> been at about the opposite side of the Sun, which would make the
EL> situation quite differet and not especially promising.
EL> However, it is worth to try to observe now also possible ouburtsts that
EL> are not from the 1-rev. trail. I can not give any timing prediction for
EL> this, other than the annual maximum.

EL> clear skies,
EL> Esko Lyytinen


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