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(meteorobs) Thinking about low radiant height
Pardon me for being slow on this, but I'm still learning
and was thinking about low radiant height and what
someone told me and what I read here, and something came
clear to me -- I think. I had been aware of two things
that reduce rates when the radiant is low -- seeing only
a fraction of the sky and atmospheric extinction. But I
finally have got that besides those two things, when the
radiant height is low, also meteors simply are farther
away and so fainter -- a third factor affecting
visibility due to low radiant height. I don't know the
math, but say when the radiant is high I see a +4 meteor
on my zenith at 80 km. That same meteor at 80 km on
someone else's zenith when the radiant is low for me
would be significantly farther away and fainter for me
-- invisible. And if I'm understanding this correctly,
kind of by definition when the radiant height is low,
the meteors are farther away, at least on average. So
there are at least three things working against an
observer when the radiant is very low: fractional sky,
atmospheric extinction, and also simply greater distance
to the meteors (inverse R-squared). Now, are those
three factors additive or multiplicative in relation to
each other? Like I said, I don't know the math. Are
there any other low-radiant-height factors to consider?
I sure wish I'd been observing with those guys in Romania
the other morning....
Ed Cannon - ecannon @ mail.utexasdot edu - Austin, Texas, USA
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