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(meteorobs) Re: Do eyes work at all?
Chris,
Interesting experiment! I feel the closer one views toward the radiant
the higher their shower perception will be. Therefore the group facing
southwest should have had the lowest perception while those facing north
should have had the highest. There is lots of activity seen in all
directions but those facing closer to the radiant can see shower meteors
diverge from the radiant over a larger angle than those facing the
opposite direction. In plain English that means someone facing north can
see Perseids heading up (south) left (west) and down (north). Those
facing south can only see Perseids that head south.
Chris, I as wondering if your resulting perception coefficients agree?
The group facing west certainly had low rates. The group facing
southwest should have done even worse.
Which directions were the two observers with the highest perception
coefficients facing? It should have been north or perhaps northwest.
It's also true that inexperienced observers will see less than a
experienced observer. This is easily seen with comparing ones data to
others for the same shower. Among long time IMO observers my perception
coefficient is very close to 1.00. If we compare my perception
coefficient to the new group of observers then it lies somewhere between
2.00 and 3.00.
This is just the tip of the iceberg. I'm certainly not all that
knowledgeable in the how's and why's of perception. This is just what I
have learned from experience.
Fascinating subject!
Bob Lunsford
Chris Crawford wrote:
>
> I have been analyzing the results of my Perseid observations for the last
> three days and I have obtained some disturbing results.
>
> The observational setup was as follows: eighteen butterfly chairs were set
> up, with four facing north, four northwest, four west, and four southwest.
> (This arrangement insured that nobody had the moon in their direct field of
> view.) The chairs incline the body such that you face an altitude of about
> 50 degrees. Whenever an observer saw a meteor, he pressed a button, and the
> time of the button-press was recorded to a tenth of a second. The computer
> equipment all worked flawlessly. A total of 360 distinct meteors were
> counted during a 2h 45m period from 1:45 local time to 4:30 local time. This
> leads to a cumulative observed rate of 132/hour. Now, before you laugh out
> loud, remember, this is a cumulative rate for all observers. Indeed, the
> average individual rate was around 25 - 30 per hour, in line with what
> others reported.
>
> Here's the disturbing part: half of the observed meteors were reported by
> less than two observers (note carefully tricky wording). The average
> observer saw only about 25% of the meteors that the group as a whole saw
> (average rate over cumulative rate). This is buttressed by the Opik
> calculations I did with one group, the west-facing group of four. These
> people got coefficients of perception of 0.14, 0.25, 0.24, and 0.23. A
> completely different calculation for the group as a whole yielded similar
> results.
>
> Now, there are plenty of serious objections that can be raised to this data.
> The first is that the observers were all utterly green civilians who had
> never seen a meteor before. Clearly such people can't give reliable data,
> and clearly, the data obtained from experienced observers will be better.
> But, how do we know that data obtained from experienced observers will be
> better? Sure, we believe it, and sure, it only stands to reason, but given
> the abysmal results from this group, even if old pros are twice as good,
> they're still pretty bad.
>
> So the question I put to this group is, what do we know about typical or
> normal coefficients of perception?
>
> Chris
>
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