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    Re: Are higher altitude sights inherently less accurate?
    From: John Karl
    Date: 2012 May 2, 19:23 -0700

    For once I disagree with Geoffrey. He says, "The error how vertical your sextant is becomes rapidly more important [at higher altitudes]. And in consequence, errors in high altitude sights will increase."

    The opposite is true. The error with sextant "tilt" is max at 45d altitude and decreases to zero at 90d altitude, for any given tilt angle, as the attached table shows.

    It is true that it's uncomfortable, even weird, swinging around in azimuth as you rock the sextant looking for vertical. Here's were the traditional half-silvered horizon mirror can help. Just keep the vertical division of the mirror perpendicular to the horizon (as you pivot around awkwardly on one foot) and your altitude error should be within reason, just as the attached table shows.

    Happy highs (altitudes),

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