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Re: (meteorobs) The formulae of ZHR
Hello Huan-Meng,
> > cos (z) = sin (h).
> > z is the zenith distance, h is the altitude.
> > So z = Pi - h, and
> > cos (-x) = cos (x) = sin (x+Pi)
>
> I think the "Pi" should be "Pi/2" in these formulae, as z+h=90 degree, but
> Pi=180 degree.
yes, you are perfectly right. It was just to test if you read my reply
carefully. =:-)))
> And at the end of your mail, if I have a right understanding, it seemed you
> wanted to tell us that the ZHR of any shower activity has a lowest limit.
> Then, what's number of the lowest limit? And can it be zero?
The ZHR can never become zero, but the longer you observe without recoding
a meteor, the closer will the expectation value of ZHR come to zero.
Just have a look at the formula again: If lm=6.5, h=90 and F=1.0 the
correction factor can be omitted and the ZHR becomes ZHR=(1+sum n)/sum(Teff).
If you watch for 1/10 of an hour an see no meteor, the expectation value
will be 10 (with huge error bars, of course!). Watching one hour
without a meteor gives an expectation value of 1, and if you manage to
watch for 10 hours without noting a meteor, the expected ZHR value is
0.1.
Cheers,
Sirko
--
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