Re: (meteorobs) Limiting Magnitude under a Full Moon


This is a tough question, especially reducing it all down to one 
average number. From my own experience, the LM under a full 
moon depends on observer perception, the clarity of the 
atmosphere, the angular distance of your FOV from the moon, the 
altitude of your FOV, and the altitude of the moon. The LM 
depends on these factors in a complex, non-linear fashion. Based 
on a fair number of observations from very clear skies on Haleakala 
on Maui, I can give some representative numbers. With the full 
moon at 30, my LM can vary from 4.5 at 10 FOV, opposite the 
moon; to LM=5.7 at 70 FOV, opposite the moon. LM around 5.7 
or 5.8 is about the best you can expect under a very clear sky, 
with full moon up 30. Typically, the LM nearer the horizon are 
affected more severely (compared to the drop-off under a moonless 
sky) than at higher altitudes. The LM overall, improves only slightly 
as the moons altitude decreases, by only a few tenths, until it 
drops to a few degrees above the horizon, at which point the LM 
rapidly starts to rise to the dark-sky level. As you can see, it is 
quite difficult to come up with a single average value, even at a 
"snapshot" in time, because it varies a lot over a wide field view 
too. You will be challenged to determine the appropriate average 
value that you seek.

Mike Linnolt.

On 24 May 2000, at 6:57, Gural, Peter S. wrote:

> Hi all;
> Can someone give me a typical value for the sky's limiting magnitude under a
> full moon for good non-hazy observing conditions.  I am working on
> simulating meteor flux rates for the 2000 Leonids and need limiting
> magnitude values for ground level, mountain-top, and aircraft altitudes
> (36000 ft) if possible.
> Thanks.... Pete
> peter.s.gural@saic.com

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