[Prev][Next][Index][Thread]

Re: (meteorobs) Plotting During the Perseids

Malcolm,

> If the sub-radiants exist, their presence or location may vary with
> particle mass.  I'd like to see if the Perseid sub-radiants claimed by
> some groups of visual observers (including plotters) are real.  So we
> want to compare like with like.  Obviously, the video field of view
> mustn't be so large as to compromise the astrometric resolution.
> 
> The limiting magnitudes will be different for the same mean magnitude
> because of the different perception factors.  Sirko will correct me if
> this is wrong, but based on telescopic observations, I'd expect a
> video system to see a higher fraction of fainter meteors than the
> visual observer given the same limiting magnitude.  

I think that depends on the analysis process. As long as you do not have
an automatted meteor search system it should not differ too much, since a
human beeing is watching the video on a telly. There you can miss faint
meteors as easily as in the sky.
But there is one more thing you need to consider when talking about the 
lm of your video system: The better the limiting magnitude, (the
smaller is the field of view and) the higher is the fraction of sporadics
in your meteor sample. This is because many (most?) meteor showers lack
faint meteors. For this very reason I would always choose a video system
with a large field of view (similar to a visual observer) when trying to
determine (sub)radiants from single station observations.
For example, MOVIE has a field of view of 60 degrees. The
measurement accuracy is about 5 minutes of arc for single meteors. That
not very good if you want to calculate orbits from double-station
observations, but good enough for single station radiant plots. In return,
you usually record more shower meteors (unless you're hunting a telescopic
shower) and also brighter meteors.
Sirko

************************************************************************** 
*           Sirko Molau             *                    __              *  
*         Verbindungsweg 7          *             " 2B v 2B "            * 
*          D-15366 Hoenow           *                                    * 
*        sirko.molau@dlrdot de         *                       Shakespeare  *
*      http://www.snafudot de/~smo     *                                    *
**************************************************************************
References: