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RE: (meteorobs) Re: Opik

Chris,
	I would suggest that guess is the wrong word. Estimate is more accurate.
	Yes, one may not be able to say that exactly 38 a second are seen (that's 
~140,000/Hr) But you can estimate that it was more than 20 and less than 
75, so this is valuable, if not precise information. When one considers 
meteor observing, much is estimated (i.e. LM, Meteor magnitude, angular 
velocity, meteor path....sort of everything), but that not mean that they 
are guesses, and therefore useless. The N1*N2/N0 is not as simple as it 
seems. From several simultaneous observation sessions, I can say that even 
when you think observer 1 and 2 saw the same meteor, that may not be true. 
Then still you must account for how many meteors would have actually been 
visible if both observers were observing under standard conditions and had 
perfect perception. While Opik's method adds more data, it does not 
necessarily clarify the picture, IMHO.

Wayne

Chris writ thusly:


Jeremie, the contradiction arises from the difference between a true count
and an estimate. Anything above 4000/hour requires the observer to simply
guess ? he just can?t keep up by counting.

The Opik double-count method is brilliantly simple. Two observers watch the
same area of sky. They keep track of N1, the number of meteors seen only by
observer 1; N2, the number of meteors seen only by observer 2; and N0, the
number of meteors seen by both observers. The probable number of meteors
that actually fell is then N1 * N2 / N0.

Chris

on 4/19/02 1:05 AM, Jeremie VAUBAILLON at vaubaill@bdl.fr wrote:


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end

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