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Re: (meteorobs) Sirko's WGN article

Hello Jeff,

> This made me think that a simple set up of one photomultiplier attached
> to a camera lens similar to that used for meteor photography could be
> employed in parallel with a meteor camera. If a computer was used to
> identify the signal 'spikes' caused by meteors - it could be used as a
> timimg device for automated meteor cameras. My main thought was to use
> this with film cameras, but equally could be employed with video cameras
> so you could then fast forward to the section of tape containing a
> meteor.

I think we had a similar thread in meteorobs some months ago. I agree
that photo multiplier may be of good use both for meteor photography and
'videography'. The Dutch observers have already some experience with such
systems. They use(d?) them for the timing of fireballs for their camera
network. If I remember correct, Hans Betlem once told me, that they could
push the gain to detect meteors down to +4 mag.
However, making an automatic system from a photomultiplier alone is
quite difficult. Just imagine what happens, if an airplane with blinking
lamps (one of the problems for video meteor detection systems ...) crosses
the sky. In addition, you dont have any information on the direction of
the meteor, i.e. on the shower membership unless ...
... you implement an idea Mirko Nitschke had five years ago, which may
or may not work (another case of an idea, which has to be tested in
practice first). It should be possible to design a special shutter, with
which you can derive the direction of the meteor without actually using an
imaging system (i.e. using a photomultiplier only). The idea is the
following: The shutter rotates at a given frequency. Hence, you don't get
a continous signal, but some kind of graph which repeats with the
shutter frequency as the stars appear and disappear behind the shutter.
Each extra light source (meteor) would give an extra spike in that
graph. Those spikes should be detectable by hardware which is doing a
1 dimensional fast fourier analysis of the signal (I actually forgot the
name of the device).
Since the meteor is moving across the sky, the position of the peak within
the spectrum will change. From the position and length of the spike and 
the shape of the shutter you can determine the position of the
light source. From its movement you can calculate the direction, speed and
the shower a meteor belongs to.
Again, this is pure theory. We will not know if it works in practice, as
long as nobody tries it.
Sirko

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