(meteorobs) The value of visual meteor observations. -Siddartha

[stange34 at sbcglobal.net]

Understood Ed.

I think your work is intensely interesting because it has a promise of 
identifying the origin or source of the meteors. (e.g., Mars remnants, 
certain Comets, Asteroids, etc.), which should have both unique 
concentration & composition of elements.

Larry
YCSentinel

----- Original Message ----- 
From: "Ed Majden" <epmajden at shaw.ca>
To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
Sent: 2007/07/29 23:08
Subject: Re: (meteorobs) The value of visual meteor observations. -Siddartha


> Wayne:
> Back in the late 1960's and early 1970's Dr. Gale A. Harvey NASA/LRC used 
> some large aperture 15-cm f/1.3 slitless spectrographs to record meteor 
> spectra.  These cameras used ASA ~8000 films which would fog after a short 
> 2 second exposure.  They developed a photo-electric meteor detection 
> shutter system that would only take an exposure when a meteor entered the 
> field.  This was an effort to obtain spectra of meteors in the +1 to -3 
> magnitude range.  Today, image intensifiers are used to obtain even 
> fainter meteor spectra.  These systems each have their own problems. 
> Image intensifiers have poor blue end sensitivity and are small in 
> aperture so high dispersion meteor spectra is not practical as you will 
> only capture a portion of the spectrum.  As an experiment I'm going to try 
> and use a Canon D20 DSLR which has had its IR-blocking filter removed to 
> obtain spectra.  This is also a small format, so only part of a spectrum 
> will be recorded.  Ideally one should use large format film 4X5 or 8X10 to 
> capture a complete high dispersion spectrum of rather bright meteors.  Too 
> bad they don't make inexpensive CCD detectors of this size to eliminate 
> film use altogether.  With Kodak getting out of the film business it is 
> becoming difficult to obtain good films for spectroscopy.  I normally use 
> Kodak Tri-X pan films for this.
> Incidentally I don't do the spectral analysis myself but have 
> professionals do this for me.  This requires expensive equipment and also 
> expertise in spectral analysis.  One has to use judgment in some cases to 
> identify some features as they often overlap which makes things difficult.
> I'm pretty sure radio detection will not work for this purpose or 
> professional spectroscopist would have investigated such methods. 
> Photoelectric systems such as the type used by Gale A. Harvey do however 
> work.  I tried to find one of these cameras on the surplus market but have 
> not had any success finding one.
>
> Ed Majden
> Courtenay, B.C. CANADA
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> On 29-Jul-07, at 9:58 PM, stange34 at sbcglobal.net wrote:
>
>> The real value is determining your own direction of "special interest" 
>> while in support of those before you.
>>
>> One of the more interesting aspects of meteor observations is Ed Majdens 
>> spectral analysis.
>>
>> If you can determine by radio detection amplitudes or other RF 
>> characterization, what meteors will produce good spectral spreads on 
>> film....you could trigger a camera with that signal possibly. This could 
>> save costly unproductive film exposures of general meteor spectral 
>> photos. That is one such specialized use or research direction possible, 
>> and it could also lead you into a new areas of research later.
>>
>> Application of Radio or Visual Astronomy is only limited by curiosity & 
>> weight of pocketbook.
>>
>> YCSentinel
>
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