(meteorobs) Fwd: Re: [IMO-News] Ursids in 2004

[Lew Gramer]

Forwarded without Christian's explicit permission.

Clear skies,
Lew Gramer

--- Christian Steyaert <lba at urania.be> wrote:
> To: "Lyytinen Esko" <esko.lyytinen at minedu.fi>, <imo-news at imo.net>
> CC: meteor at ml.free.fr
> From: Christian Steyaert <lba at urania.be>
> Date: Wed, 22 Dec 2004 22:14:29 +0100
> Subject: Re: [IMO-News] Ursids in 2004
> 
> The radio observations on
>          http://radio.data.free.fr/main.php3
> 
> in particular those of Algeciras, Swan and Entwistle support relative high 
> activity for the period Dec 22 12-14h UT.
> 
> The rather small daily radiant movement makes the interpretation of these 
> counts the easiest of all streams.
> 
>          Regards,
>          Chris
> 
> At 09:18 21/12/2004 +0200, Lyytinen Esko wrote:
> >We have computed with Markku Nissinen old trails from the Ursids parent
> >comet 8P/Tuttle, in order to trying to find good encounters for this
> >year.
> >
> >
> >The trails possibly involved are about a thousand years old, so even the
> >comet motion is quite uncertain. We report now what we have found. The
> >encounter with the trail from 1048 looks promising at first. It however
> >appears that the da0 is too big for good number of visual meteors
> >produced. An analogy with the Leonids model gives the ZHR around 1 or
> >smaller. This encounter is in December 22 at about 01 to 02 UT.
> >
> >
> >Older trails from 801 to 856 seem to give meteoroids near the Earth
> >orbit at roughly the end of this year.
> >These very old trails are very strongly scattered and the trails look in
> >the graphs that I made like scattered clouds. In general the Earth
> >encounter seems to be in the center of these wide clouds. For some
> >reason it however appears that much of the surrounding regions, both in
> >time and in rD, are more occupied than the near Earth region.
> >
> >
> >These encounters happen almost half a day after the 1048 encounter.
> >There are first, at about 10 to 11 UT,  encounters with the trails 829
> >and 843 with small meteoroids (quite a big da0) and then from about
> >11:30 to 14 UT with somewhat bigger meteoroids from the trails 801, 815,
> >829 and 856. The trail 829 has clearly sections in both these groups.
> >
> >
> >Even if the comet motion were accurate enough in our backward
> >integration, we do not give any clear prediction of outbursts even from
> >this old trail grouping. The rates are probably very low. We give the
> >times however for those wanting (if being able) to try to observe.
> >
> >
> >It may even be that if the comet motion is slightly off from our nominal
> >solution, there may be higher rates from these trails and/or from some
> >others. There can also be activity from even older unmodeled trails.
> >
> >Clear skies etc
> >Esko Lyytinen
> >Markku Nissinen
> 
> Yahoo! Groups Links
>     http://groups.yahoo.com/group/imo-news/


=====
Lew Gramer <dedalus at alum.mit.edu>


		
__________________________________ 
Do you Yahoo!? 
Yahoo! Mail - Helps protect you from nasty viruses. 
http://promotions.yahoo.com/new_mail