(meteorobs) Ursids in 2004

[Esko Lyytinen]

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