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    Re: Finding IC for A-12 bubble sextants
    From: Art Leung
    Date: 2021 Oct 11, 05:33 -0700

    David Pike, you wrote: "You and me both for the A12.  You might like to try a technique I’ve found useful when calibrating my periscopic sextants"

    It sounds like you have a pendulous mirror type rather than a bubble type.  I do something roughly similar with my bubble tho I tend to use this technique mostly with stars.  Since I'm on the ground near sea level and looking thru the murk, even bright stars can be dim the point of invisibility.  I find that I will "lose" the star for a few seconds and I keep tracking with the index knob - when the star re-appears, it's usually pretty close to the center.  I then "cheat" a bit - if i find the object is a bit low in the bubble, I will sometimes adjust the bubble so it is a little high and then bring it back to center.  I get good results with it so maybe it's harmless?

    -- Arthur

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