(meteorobs) Earth grazer ID from single station

[stange]

Addendum,

It appears the same methods can be used to determine if a meteor is moving 
away from the observer or toward the observer. And that would put us a 
little (closer) to being able to determine its apprx. location as a form of 
single photograph triangulation.

YCS


----- Original Message ----- 
From: "Gural, Peter S." <PETER.S.GURAL at saic.com>
To: <meteorobs at meteorobs.org>
Sent: 2008/09/25 17:17
Subject: Re: (meteorobs) Earth grazer ID from single station


> YCSentinal;
>
> It may be possible to identify a grazer from a single station video record 
> by examining the change in apparent angular velocity across the entire 
> trajectory. You would need angle rate from each frame and a well 
> calibrated field of view that accounts for wide field distortions (3rd 
> order or barrel for fisheye lenses). There is a closed form expression of 
> the apparent angular velocity as seen from the camera that changes with 
> radiant distance, entry velocity, and range. It likely has an inflexion 
> point at CPA and thus could be used to id a grazer. I will have to work on 
> this to see if there is any characteristic to the changing values that 
> could be used to advantage. One normally only considers meteors dropping 
> from higher to lower heights so this has been largely ignored from the 
> perspective of numerical solution. For long length/duration meteors, it is 
> actually possible to solve for the radiant position from the changing 
> angular velocity observed. One issue however may be that very wide field 
> cameras won't have sufficient angular resolution to discriminate changes 
> in the angular velocity.
>
> Pete Gural
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