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Re: Radiants, was Re: (meteorobs) A blank meteor reporting form



Hi again,

I guess I get what George means and basically I agree with him. There 
indeed is always some 'subjective' part in classifying: e.g. whether you 
saw the meteor in the corner of your eye, or in the center (in other 
words, how sure you are about the direction and path).
As mentioned in my previous mail, I use a standard diameter of about 5-10 
degrees for all streams, but with a subjective factor 'on' it as George 
is indicating too. And he is right that it has little meaning to use 5 
degrees for one and 10 degrees for another stream. Except perhaps for 
using a larger diameter for those streams you know have diffuse radiants 
(e.g. alfa Capricornids).

Concerning the supposedly more 'accurate' photographic radiant diameters: 
please note that our Dutch Photographic Survey has shown for several 
streams that the radiant is more compact than previous studies have 
indicated. There is still a lot of bad quality data in some photographic 
analysis, and uncertainties in determined radiant positions are seldom 
incorporated (and can be large in some cases!).
Even some streams that are sometimes listed as 'rather diffuse radiants' 
are actually quite compact if you restrict to the good quality 
photographic data.

- Marco Langbroek


References: