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    Re: Agnostic gnomon and horary error
    From: Robin Stuart
    Date: 2024 Jun 3, 09:42 -0700

    I did some quick measurements in Photoshop of the scanned image and find that the E-Zenith-W circle is seen as an ellipse of 302pixels by 34 pixels and the horizon circle is an ellipse of 298 pixels by 52.4 pixels. This places the observer 10.1 degrees below the plane of the horizon circle and 6.5 degrees north of east. These are quite modest in size and not enough to throw off Chuck V's suggested approach. If the gnomon is angled at the co-latitude this would give an angle in the photograph of 48.9 deg. I measure it at roughly 48.0 which seems consistent.


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