Re: Encke Minimum in 7"?

This subject keeps coming up. Each time we get differing opinions. I
would like a decent explanation of why the division is usually visible
only at the ansae and only in perfect conditions. In anything but
perfect conditions it is patently not visible.

A "contrast effect" suggests that the illusion should be visible on
many more occasions, to many more observers, with other than perfect
seeing and with other than larger instruments.

If I saw it once as clearly as I see the washing line in my back
garden. But then never saw it again. Does that really make it
impossible to see in my 6" refractor under mind-boggling excellent
seeing conditions? I think not.

Regards
Chris.B

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