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Re: (meteorobs) Lew's video meteor system
Detlef Koschny wrote:
> I agree if this means geometrical distortion - it is easy to correct in a
> subsequent computer analysis. However, image distortion - i.e. point stars
> not being points at the edge of the field of view (FOV), but elongated
> blobs - is annoying and should be reduced.
Try to find someone who worked on the Astro II Star Tracker at JPL.
They have soved this problem for a widefield camera in a realtime 3 axis
tracker.
Basically the technique is to centroid each blob. Since you "know" that
each blob was created by a point source, the centroid of the blob can be
corrected for the image distortion at that point via interpolation of
test data. ie you know how much the centroid of blobs in that region
varies from the location of the centroid of an ideal imaged point
source. Since the geometrical distortion is removed by a similar
algolrithm, I believe that they combined the two corrections into a
single interpolation.
Given software, the image distorions of low quality optics do not impair
astrometry so long as the relationship of the optics and ccd are fixed.
If anything is adjustable, electronically variable, or moves from
thermal or mechanical (such as variances in tube bending as a unknown
function of scope orientastion) effects all bets are off!!! The Astro
II was incredibly precise give its simplicity and low cost.
Regards,
John
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