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Re: CCD-V Vs visual observations Dear Richard, > I have been watching the discussion of R CrB fading. Why is > this star not a target for CCD imaging? It would be very easy > to make images with a small short-focus lens at 1 minute > intervals, and the result would be impersonal and free of the > devastatingly huge scatter in the visual estimates. Long focal-length instrument is not adequate for this purpose, as you can see. In practice with short-focus lens with a CCD, the accuracy is known to strongly depend on the combination and the condition. This is probably because the stellar PSF can become comparable or smaller than the CCD pixel size, which makes precision photometry very difficult or sometimes impossible. I know similar experiments which could only yielded a 0.1 mag precision. I wonder if there is a well-established setup for wide-field precision CCD photometry. Regards, Taichi Kato
Return to the Powerful Daisaku Nogami
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