(meteorobs) Perseids from Switzerland

[Marco Langbroek]

Geert Barendsen wrote:
> You are right about the high ZHR's. Our limiting magnitudes have been 
> systematically underestimated for the past 10 year. I have wondered 
> about this a lot because we do everything right (e.g. count in at least 
> 3 or 4 fields, make sure the fields are at sufficient elevation, take 
> Lm-gaps and negative outliers into account, etc...)

hi Geert,

One reason could be that you do not use averted vision while counting, but only 
your less-sensitive central vision. You should use averted vision, after all 
most observers (but there are exceptions) do see a lot of meteors in the corners 
of the eyes too.

Also, at least with Dutch observers (so probably with Belgian too) there was a 
long standing mistaken thought that visual limiting magnitudes would always stay 
< +5.5 to +6.0 in our light polluted countries. Hence obsevers did not even 
realy try. In reality, even in the Randstad (the urban part of Holland between 
The Hague, Amsterdam and Utrecht) I usually easily reach +6.0 when a few km 
outside a city under good weather conditions, and in the countryside outside the 
Randstad under good conditions go well over +6.5. Whenever I see conditions 
described as "good" but reported Lm's below +6.0, I know there is an Lm problem 
with the data.

- Marco  :-)

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Dr Marco Langbroek
Dutch Meteor Society (DMS)

e-mail: meteorites at dmsweb.org
private website http://home.wanadoo.nl/marco.langbroek
DMS website http://www.dmsweb.org
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