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Re: (meteorobs) Request for data

Wayne finally has time to get some pennies out and throw 2 cents in hither 
and thither:2 LM methods are in use.

(1)  Observer determines his limiting magnitude from stars at the
>zenith, and judges all meteor magnitudes by comparison to this area.
>
>(2)  Observer determines limiting magnitude from stars within the
>field of view, and judges meteor magnitudes from stars in this field.
>
>Method (1) was used more frequenctly in the past, while method (2) is
>the most commonly used today, though I have still heard a few observers
>on this list reporting their limiting magnitude from zenith stars.
Lew observes:->
>In fact, according to discussions on meteorobs last year, the "standard"
>IMO method (and so possibly the one used by the majority of observers
>here?) is actually the first! I began by using LM count areas SCATTERED
>around the sky, with the idea that these would average out any variations
>in LM across the sky due to high atmosphere haze, light pollution domes,
>twilight, etc. But I was quickly corrected by more experienced readers of
>meteorobs, that IMO LM count areas should in fact be chosen as close to 
>the
>ZENITH as possible! 
Hmmm, I'm not sure that's where the discussion ended. Bad memory I guess.
>So how about it, guys: is this the method used by most
>IMO observers now?

One difficulty in using only the zenith measurement, is finding an LM 
polygon up there! The "stars of Ursa Minor" method is not applicable, since 
that is centered around 30-50 degrees elevation in the US. If you only 
count the area closest to the zenith, that is only one polygon, with 
resolution/accuracy limited to that available in that one only. What I have 
been doing is counting the area closest to the center of my FOV, and any 
surrounding ones with a 50 degree radius (As indicated in Peter J's paper 
that is his general area of meteor detection..dot it may be higher or lower 
for others.) Perhaps a solution, which would provide useful info for 
examination is to include 2 Limiting Magnitude fields...one labeled "z" for 
zenith, and another "f" for Field of View. Something like:
z  +5.8@0145
f  +5.6@0145

This would allow the collection of data to allow comparison of the methods.
However, since these are used for the reduction of raw counts to ZHR's, 
it's kind of a circular situation, since there is no "right" answer to the 
actual ZHR question, each correction factor will just create a different 
ZHR.


Lew again:
>Regarding the two methods of meteor magnitude estimation, I have to admit
>that I actually regularly use both! It could be because my
>magnitude-estimating skills are not practiced enough to be "innate" yet,
>but I frequently find myself correcting magnitude estimates by doing
>comparison with stars NEAR where the meteor was observed. In fact, as my
>knowledge of good comparison stars around the sky grows, I actually do 
>this
>MORE often. 
	 Once again, I am focused on my Field of View, and therefore that is 
the area where I know the most magnitudes on a particular night. Of course, 
back when the weather was better, I had a pretty good feel for most of the 
sky, but lately, I have to study fuerst (HaHA).
	I generally compare the meteor to the closest star to it with a 
similar magnitude. I guess that's a good case for recording meteor 
elevation data. ( I do note this in comments for low elevation meteors 
where the atmosphereic extinction is signifigant...< 30 degree elevation)
How bout others? I know many must have answered this in the past, but I do 
not recall the methods that experienced/prolific observers use.

Wayne