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Re: (meteorobs) Re: North Apex and Leonid meteors
Thanks to Paul and Bob for posting on this interesting thread!
> The activity period for the Leonids has nothing to do with
> the Northern Apex meteors.
A final follow-up on this topic: The IMO does not recognize the
"Northern Apex" as a shower at all, I believe - instead, the IMO
recommends that observers merely label these as "Sporadics". And
of course, the activity date for the Leonids is also reckoned by
the IMO as being 14-21 November - despite this fact.
So as Bob mentions above, the short period of recognized activity
for the Leonids is a direct result of the narrow traverse of the
dust stream which causes the Leonids, relative to Earth's orbit.
However, as it happens the only way that we visual observers can
CONFIRM the short activity period of the Leonids, is because our
observations show the Leonids being lost in "sporadic pollution"
prior to 14 November, and after 21 November. That is, before 14
Nov and after 21 Nov, there is no statistically valid way for a
VISUAL observer to distinguish Sporadic activity from "late" or
"early Leonids". So in actual fact, outside of these times, the
Leonids ARE in effect becoming confused with Bob's Northern Apex
"radiant", as well as the many other Sporadics this time of year.
Of course, the situation may be quite different for observers who
use other techniques like telescopic plotting, intensified video,
or backscatter (radar) to identify shower meteors. For such more
accurate and "deeper" (higher Limiting-Magnitude) methods, I ex-
pect that the Leonids may show themselves statistically against
the background of Sporadics for at least a slightly longer period?
Clear skies,
Lew
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