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    Re: Southern sky CN photo puzzle
    From: Frank Reed
    Date: 2023 Sep 11, 06:07 -0700

    Oh good, Antoine! I was specifically slowing this one down in the hope that you might see it before it was finished. It struck me as the sort of puzzle that you usually enjoy. :)

    I agree with all your conclusions and identifications of stars. And yes, the image is difficult.

    As I see it, the photo has two main problems that work against us. The aurorae were clearly the photographer's target so I understand that. This photo, like many recent digital photos of large portions of the night sky, also has annoying "dynamic range" by which I mean to imply that bright stars and faint stars (with the exception of the very bright, like Sirius, Canopus, and Achernar) all look more or less alike. This means that we have to hunt for distinctive geometric patterns without regard for brightness. For example, I found Diphda by looking for a pair of triangles of stars, directly above Diphda (so south of the star) in the photo and then comparing against a star chart (I used an old copy of "Norton's Star Atlas" at first and also compared against "Stellarium"). It's certainly difficult to see, but I'm quite confident that it's Diphda thanks to that unique pattern of faint stars.

    Frank Reed

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