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Old 12-12-2011, 09:32 PM
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irwjager (Ivo)
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Join Date: Apr 2010
Location: Melbourne
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Quote:
Originally Posted by Merlin66 View Post
  • For unsaturated star images, the maximum size of the star is similar to the Airy disk in diameter.
False. The Airy Disk does not have a diameter. It is a pattern, patterns don't have diameters. You could, however, say that 83% of all starlight of the imaged star should be contained within the area that extends from the center to the first minimum.
Quote:
  • The FWHM of the star image is reasonably constant.
False. The FWHM is dependent on how well you can fit a Gaussian curve to a star. You will be able to fit a Gaussian curve less well to saturated stars, depending on the response of the CCD you're using. It is also neigh impossible to fit a gaussian curve to undersampled images.
Quote:
  • As the star image saturates, the “flat top” extends out to the diameter of the Airy disk.

False. It can extend way beyond the first minimum.
Quote:
  • Also, for saturated star images the “wings” include additional energy from the outer rings, and can extend, in linear diameter, to and slightly beyond the dimensions of the 1st Airy ring.
False. They extend throughout the whole image.
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