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Re: (meteorobs) coefficient of perception
On Thu, 16 Aug 2001, Tom Fleming wrote in response to Bob Lunford:
> the coefficient p may be represented as a product of two factors, p=(chi)(pi)
> the (chi) factor is the same for all observers and depends only on
the apparent mag. of the meteor. It is unity (100%) for meteors of the 1st magnitude or brighter and drops to about 0.1 for 5th magnitude meteors.
> The second factor is the location of the meteor in the observer's field of view. It decreases from 0.8-0.9 near the center to 0.2-0.5 at the boundary.
Bob was talking about the product of these two terms averaged over the
whole fied of view. Hence the disagreement is not an order of
magnitude. Some leeway is needed for differing limiting magnitudes and
fields of view (boundary angle).
The Oepik expeditions were in Arizona long before light pollution, so
I'd imagine a +5 meteor was 2 mags or more above the naked-eye limit.
The AKM study of a decade ago found a perception coefficient for delta
mag. of 2 was 10% at ~25 degrees from the centre of vision. If the LM
is a magnitude worse now, the odds of detection drop to 2% for a +5 at
the same angle.
Given the uncertainties I don't see any strong conflict between Oepik's
and Bob's figures.
Malcolm Currie
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