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Re: (meteorobs) Very Fast Sporadics

In a message dated 98-09-16 09:46:10 EDT, you write:

 
 Lew>>Thanks for the "Technique Notes" on George's Speed Scale... Looks like I
may have been using the Speed Scale differently all this time! Somehow I
always 
 interpolated George's comments that "Very Slow" meteors were rare, to imply 
 that "Very Fast" meteors were also rare. Tain't so, it seems!<<

Very Slow meteors are relatively rare compared to the other speeds...these
would be from meteors with entry velocities of 20 km/s or less or very short
stubby meteors right next to a radiant.  I don't think I've implied that Very
Fast meteors were also rare?
 
 Lew>>So then for George, it's NOT fair to say Very Fast Sporadics in the AM
are 
 unusual... (Though for myself, I still can't get away from seeing a
qualitative 
 difference between Perseid and Leonid speeds? Come to think of it, I see the 
 occasional meteor that APPEARS even faster than an average LEO!)<<

You may be able to see the difference between the speeds of a perseid and a
Leonid...but with the scheme of determining shower associations it's not
necessary when you apply the other determining factors. I see meteors on
occasions that I think are faster than a Leonid...but these I still lable on
the speed scale a 5. At these speeds, it would serve no purpose to make an
estimate. If you have a cluster of Very Fast meteors radiating from an area, a
5 would still indicate relationship. The human eye/brain is only so accurate.
Specialized measuring equipment would be more useful in these instances. Such
as radar or camera's equipped with rotating shutters etc. Meteors at
hyperbolic speeds apparently have been detected by various means. It seems
that about 1% are at hyperbolic speeds...that is traveling faster than the
Leonids up to 100 km/s. 
 
Lew>> Well anyway, I still end up thinking George's 5 meteors sound
suspiciously like 
 DAUs, or else from a related radiant - would y'all agree?
  >>

Determining shower relationship via vote is not how it's done I'm afraid? They
are judgement calls from the individual observer who hopefully knows how to
interpret what they see? Three would be within the realm of calling them
DAU's, but their location and my confidence of relatively accurately lining up
with it's trajectory at the time is quite high. High enough for me to not be
too hasty in calling them something else. But the two with trains are
definitely not coming from the DAU radiant despite their relative closeness to
it. Particularly the one that traverses thru the radiant. The other had a long
lasting train of 2 seconds...and it was relatively long enough to get a good
alignment with the cord. A 1 or 2 second train gives you plenty of time
usually to adjust and fine tune the cord's alignmen nearly right on. 
GeoZay
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