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RE: (meteorobs) query on sporadic meteors

SAG is actually the best one to use for "counting" type observations; if 
you are plotting, then you can try and pin it down to the specific 
(individually weak) centers of activity, however they still should be 
reported (To NAMN and IMO) as SAG's, with the specific radiant reported in 
the notes for each meteor.

Right Guys?

Wayne

----------
From: 	Kim S. Youmans[SMTP:ksyo@pinelanddot net]
Sent: 	Friday, May 14, 1999 1:51 PM
To: 	meteorobs@jovian.com
Subject: 	Re: (meteorobs) query on sporadic meteors

Hello!
        The question on sporadic activity, in particular, about how high a 
rate
is too high, resonates with me as I just finished an observing session this
morning with a quite high sporadic count.  The final hour before dawn (when 
I
naturally expect to see the most) produced 13 sporadics and 4 ETA's.  I 
noticed
a cluster of radiants in Sagittarius are active now;  my main question is
this....if I trace a meteor back to this "cluster" of radiants, but can't 
peg
down exactly which radiant as they are all so close together,  is there a
single three letter code I could use, like SAG, the denote this 
"generality?"
                                           Outbursts, everyone!   Kim S.
Youmans


Wayne T Hally wrote:

> ----------
> From:   Michael Mattiazzo[SMTP:mmatti@yp-connectdot net]
> Sent:   Friday, May 14, 1999 11:07 AM
> To:     meteorobs@jovian.com
> Subject:        (meteorobs) query on sporadic meteors
>
> Hello all,
>
> This is my first query post.
>
> What is the definition of a sporadic meteor?
>
> Does it mean that the meteor observer cannot associate it with any known
> meteor streams?
>
> Technically, any known or detectable meteor stream
>
> But aren't all sporadic meteors associated with meteor streams (whether
> known or unknown to the observer)?
>
> Hmmm, well yes and no. Is one meteor in an orbit that no other particles
> share a meteor stream? That seems like a clear no. Are 10? Well
> maybe...what if the 10 are spaced in a 200 year orbit so one meteor
> approaches the earth on average every 20 years? What if they are packed
> together and all 20 occur in one night..but are observed at 20 different
> locations?
>
> Meteor Stream> "A stream of solid particles released froma parent body.
> Various ejection directions and velocities cause the width of the stream
> and (along with other factors) the gradual distribution of meteors over 
the
> entire avaerage orbit"
>
> If I observe 2 sporadics radiating from the same point in the sky during 
a
> 1
> hour interval, can I assume that they are related to an as yet 
unrecognised
> stream?
>
> That would not be a good assumption. If however, you observe 2 and 20 
other
> people on earth also observe 2 the same night, AND THEY ALL HAVE THE SAME
> VELOCITY, then yes they may well be a shower or outburst. That is exactly
> why we plot meteors, so that worldwide observations can be combined to 
see
> if any particular activity rises above the background of pseudorandom
> "sporadic" meteors.
>
> If I observe 6 sporadics in an hour, is this count too high?
>
> Not at all...in Autumn, hourly sporadic rates can be much higher than 
that.
>
> The key really is detectability. A shower with a rate much below 1 an 
hour
> is undetectable by most means. The rate is so low, photographic records 
are
> unlikely, and other methods lack sufficient accuracy at such a low rate. 
So
> they become the sporadics. And there are many particles in their own 
orbit.
> When streams spread out so much they can't be detected, they become part 
of
> the soup. When streams get too close to a planet they can be disrupted 
with
> the particles scatted across the solar system.
>
> A related point, sporadic meteors are not truly random. A large 
percentage
> fall on or near the ecliptic, since that's where most of the "stuff" of 
the
> solar system is. And they tend to approach the earth on orbits that cause
> concentrations to appear. In addition, particles that are inserted into
> orbits well out of the plane of the solar system tend to remain in stable
> orbits (since they don't interact with the planets as often), hence there
> is a concentration of particles in what are called "toroidal" orbits.
>
> Not a very organized or satisfying reply, but I'll bet it gives you more 
to
> think about (and probably will spark a few more question!!)
>
> Cheers and clear skies with plenty of meteors,
>
> I'll take that! Same to you.
>
> Michael Mattiazzo,
> Wallaroo, South Australia
> mmatti@yp-connectdot net
>
> Wayne T Hally
> High Bridge NJ USA
> meteors@eclipsedot net
>
>                      Name: WINMAIL.DAT
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>
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