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Index error test with Davis whole horizon mirror
From: Erik Rosen
Date: 2023 Sep 14, 06:13 -0700
From: Erik Rosen
Date: 2023 Sep 14, 06:13 -0700
I have a Davis 25 sextant with a "whole horizon mirror". I think that's what they call it. It's not split into a mirrored side and a clear side.
What's the best way to measure the index error on this sextant? The usual ocean horizon test that I find in books doesn't work well. It's diffiult to see two horizons when they are close together. The Sun test doesn't work since the shades in the horizon direction aren't dark or dense enough. I need something that I can test easily, on the spot as I'm taking sights. Any ideas?
Erik Rosen
