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(meteorobs) Re: Swift sporadics



Lew Gramer wrote:
> 
> Howdy, Bob - definitely worthwhile mentioning that sporadics in the AM are
> generally faster than sporadics in PM... As you said, they get the Earth's
> zippy 30 km/sec added to their own orbital velocity!
> 
> But I think George generally only considers a meteor "Very Fast" (a "5" on his
> and NAMN's speed scale) when it is travelling at, say, Perseid speed or better,
> to use a convenient baseline... Is that fair to say, George?
> 
I will let George answer this...
>
> And even with the added "boost" of Earth's motion, aren't there pretty few
> sporadic meteors that will hit us at better than 59 km/sec? Anyway, I know from
> the little observing *I* have the chance to do that I very rarely see anything
> I classify as a "5" on George's scale, unless a Very Fast shower (ETA, PER,
> ORI, LEO, etc.) happens to be active... (In fact, I tend to log even PERseids
> as "4", and only a rare long one as "5".)
> 
> OTOH, I could be wrong! :)
> 
Lew,

There is a area in the morning sky centered on the Earth's apex that can
produce meteors with velocities in excess of the Perseids. I would
estimate that this area covers one quarter of the morning sky. Since
that is a big chunk of sky I would not consider "Very Fast" meteors as
rare.

This discussion is another reason why I favor the IMO's endorsement of
measuring meteor velocities in degrees per second and not the vague
numeric scale, at least for experienced observers.

Bob

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