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Re: (meteorobs) RECENT METEOR SESSION



In a message dated 96-11-18 19:24:42 EST, you write:

<< >4.Are my speed notes correct?
 The speed doesn't actually refer to how long the meteor lasted, but how
rapidly 
 it covered the sky. Almost all the meteors you see will last less than 1
second. 
 But suppose you saw one that lasted (in the ballpark of) 0.5 second. If it
only 
 covered a few degrees of the sky, you'd call this a very slow meteor! If on
the 
 other hand, you saw it arc all the way from western Orion into eastern Aries
in 
 that 0.5 second, it would be a VERY fast meteor! Basically, as George will
tell 
 you, this 0-5 "NAMN speed scale" is designed to be a subjective impression
of 
 how fast the meteor appeared to move in the sky. (George invented it!)<<

Yes I "invented" the current method that I use because when I first started  
to observe meteors from IMO's 1989 Meteor Observing Handbook..dot it didn't
mention anything about how to determine "speeds"...just that it needs to be
done. I noticed on IMO's Fireball Report form a scale of 0 to 5. This made
sense to me and soon was on my way to making up my speed scale. Along the way
there were some inconsistencies that I had to deal with, but I think I've
answered them satisfactorily. It actually has evolved over a period of time
to it's current form. Since then I've also found out that a form of a 1-5
speed scale already existed in the past.  I never seen it in writing yet, but
I have no doubt that it existed somewhere in some form. But I believe the
difference between my speed scale and the ones that may have existed in the
past is my use of a "groups of three scheme" when judging shower membership.
I see there is an example to work on below and will explain it there a
little.
 
 >>For instance, almost all the Leonids you saw this weekend should have been
4s, 
 with a few 3s and 5s. (The Leonids are a very fast shower!) If you saw any 
 Taurids, though (very slow!), they should have been mostly 2s and 3s, and
maybe 
 one or two 1s if you were lucky to see a rare slow meteor!
 Lew<<


Using the Leonids as the example above...A Very Fast meteor shower.  It's
Shower Base Scale number is determined to be 5(see the October 1996 revised
instructions on how to determine this). Using the groups of 3 scheme, it's
members will display speed scale numbers of 5,4 and 3 for most areas of the
sky except for 3 easily recognizable exceptions(covered in the instructions
as well).  The Taurids are considered Slow...Not Very Slow I mind you.  Their
Shower Base Scale number is 3.  Again using the groups of 3 scheme, it's
members will display speed scale numbers of 2,3 and 4. Again you will have to
take the possible exceptions into consideration. 

If anyone is interested in getting emailed to them the more completed paper
that I have written on how to use this scale, please contact me and I will
send it to you.  I have several examples shown. Also, if you have only an old
version and would like to be updated, you might want the more current
version. 

George Zay