(meteorobs) Re: Visual Plotting

[Kim Youmans]

Ed,
       >>>Only very experienced observers with high familiarity with star 
positions came close to good plots.

My thoughts *exactly*.  If the observer is not familiar with the star 
positions, so much time will be wasted in finding the spot to plot, that 
accuracy (read: memory) will be lost.

   One way around this (though time consuming) for an unexperienced plotter 
is to "anchor" the path in the sky using a pencil, cord, or short rod.  The 
key here is being VERY sure you can put that pencil back up in the sky in 
exactly the right place,  AFTER you have been looking down at your charts 
trying to find the same location on paper.  So you spend a few seconds 
recording that spot in your mind so you can get back to it.

    Ed also noted that even the experienced observers "came close."  I'm 
willing to bet that few if any were ever truly "spot on."

Kim Y.
----- Original Message ----- 
From: "Ed Majden" <epmajden at shaw.ca>
To: "Global Meteor Observing Forum" <meteorobs at meteorobs.org>
Sent: Monday, August 08, 2005 6:28 PM
Subject: (meteorobs) Re: Visual Plotting


> on 8/8/05 14:26, Kim Youmans at meteorsga at bellsouth.net wrote:
>
>> If  I may add to what Felix and others have already noted, the accuracy
>> notation would also have to do with confidence in the actual placement of
>> the plot line on the map -- how sure is the observer that he/she has 
>> plotted
>> the meteor correctly.
>>
>> This is important, as I have witnessed three *experienced* observers plot
>> the same meteor (myself being one of the three)-- a bright -2 with a long
>> path length -- differently.  Not *too* differently, but  with such a long
>> path length, more error will creep in, and establishing a radiant would 
>> be
>> quite difficult.
>>
>> Just my 02/100 of a dollar...
>>
>> Kim Youmans
>>
>    I agree with Kim.  We used Dominion Observatory Sterographic Projection
> Meteor Plotting Charts back in the 1950's.  See: Meteor Science and
> Engineering by McKinley, Fig. 3-2 on page 49 in my hard cover edition.
> Errors did creep in.  Only very experienced observers with high 
> familiarity
> with star positions came close to good plots.  It would be an interesting
> experiment to check plot positions against a guided photo of the same 
> meteor
> track.  The visual track would of course be longer because the eye is more
> sensitive than film.  Perhaps this could be tried with a sensitive video
> recording system today.
> It would be interesting to see the results of such an experiment.
>
> Ed Majden  B.C. - Fireball Network Coordinator
> West Coast Sandia Bolide Detection Station
> Courtenay B.C. CANADA
>
> http://members.shaw.ca/epmajden/index.htm
>
>
>
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