[Prev][Next][Index][Thread]
(meteorobs) Fwd: [IMO-News] A weak Ursids outburst possible in 2002
[Forwarded without permission of the author.
Lew Gramer <owner-meteorobs@atmob.org> ]
> -----Original Message-----
> From: Lyytinen Esko [mailto:esko.lyytinen@minedu.fi]
> Sent: Monday, December 09, 2002 2:59 AM
> To: imo-news@imodot net
> Subject: [IMO-News] A weak Ursids outburst possible in 2002
>
> We have searched for possible encounters, this December, with
> old Ursids trails left from the parent comet 8P/Tuttle.
>
> The most promising trail appears to be the very old trail
> from the year 1090.
>
> This trails is of course very strongly disrupted. According to
> the modelling, meteoroids from this trails seem to have some
> clustering near the Earth orbit at the correct time this December.
> Possible encounter can be at two completely different sections of
> the trail, these making further 'foldings'. Especially the one
> with larger da0, seems to consist of a wide range of da0:s (could
> be divided further to at least three sections).
>
> Using the solar radiation pressure to cause the da0 in the model-
> ling, the encountering sections correspond the beta values of
> about 0.00041 or 0.00042 and 0.00059 to 0.00070
>
> The smaller beta value has the most close encounter in the nominal
> solution A2=0, but this situation is preserved only with quite a
> small range of the A2-values near zero. At the higher beta values,
> it is the "A2-effect", (negative values) that seems to bring the
> particles more close to the Earth orbit.
>
> The encounter with the smaller da0 is predicted at solar longitude
> 270.71 or 270.72 and the other at solar longitude 270.76 to 270.82.
> The former is expected to contain brighter meteors. The peaks are
> expected to merge into each other with a more or less gradual
> dimming of the meteors.
>
> We can't give any ZHR value and not even tell which one of the
> trail sections will give the higher ZHR. The parent comet early
> motion uncertainties grow quickly when we compare for example
> the returns around 1100 to those near 1400.
>
> We can not be even certain of any apparent trail encounter, but do
> expect that the encounters are strong enough to be detected
> and give ZHR above the background. In 2000 the beta value was about
> 0.0011, so the meteors are now expected to be generally brighter.
> Because of the full moon this is an important factor.
>
> The times are:
> 2002,12,22.79 or about 19:00UT, for the first section encounter
> 2002,12,22.86 or about 20:40UT, for the second section encounter
>
> Esko Lyytinen
> esko.lyytinen@luukku.com
> Markku Nissinen
> markku.nissinen@pp.inet.fi
>
>
> http://groups.yahoo.com/group/imo-news
>
> --------------------------------------------------------------
The archive and Web site for our list is at http://www.meteorobs.org
To stop getting all email from the 'meteorobs' lists, use our Webform:
http://www.meteorobs.org/subscribe.html