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RE: (meteorobs) Moonlit Leonids
Dear Tony,
> (1) For a meteor shower with a Leonid-like population index,
> by what factor will a full Moon reduce the number of
> naked-eye meteors?
The first problem here is what is a Leonid-like population index? The value
for the normal activity is 3 - 3.4. During the outbursts it can/will be
different and it will vary during the peak. Last year the value was about
1.7 around the peaks and up to about 2.2 during the peaks, for now I'll
assume 2.0.
A limiting magnitude of 5.0 should certainly be possible in the right part
of the sky. This would mean that the number of visible meteors would be
reduced by a factor of 2.0^(6.5-5.0) = 2.8 compared to a mag 6.5 sky.
Considering the low altitude of the moon (if you are in the right location)
I would not be surprised if an LM of 5.5 can be achieved, resulting in a
factor of 2.
So, a reduction factor of about 2 to 3.
> (2) How much could you hope to improve your limiting
> magnitude on a Moonlit night by, say, moving from a
> sea-level site with moderate humidity to a dry
> high mountain observing site ?
This would ceratinly improve things, though I'm not able to say how much.
Not only will this reduce the lunar interference, but also the sky closer to
the horizon will be darker.
> (3) Can you offer any tips in general for observers who want
> to reduce the effects of lunar interference during the coming Leonid
storm?
For the first peak, at 4 UT, in Western Europe the moon will be quite low
above the horizon (while twilight is approaching). At 10:30 UT, during the
second peak this will be the same for the Eastern US I think (if Boston is 5
hours behind UT). Too far to the east might not be good though. In Boston
twilight will begin before the predicted peak time. Maybe Kansas, during the
peak the moon is 21 degrees above the horizon with an hour to go before
twilight. Anyway, you'll have to find a latitude where the moon is as low as
possible, but where you'll still have some time before twilight.
While observing keep the moon behind you. An observing site where you have a
clear view to the east but some obstruction hiding the moon in the west
could help.
Yours,
Daniel van Os
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