Which navigational error increases when a 18th-century sextant’s horizon mirror is misaligned relative to main frame perpendicularity?

💡 Explanation

When the horizon mirror tilts from perpendicularity, 'side error' occurs because the reflected horizons are tilted, increasing geometric distortion toward higher altitude celestial bodies. Therefore errors will increase with target altitude, rather than midday, latitude, or speed, which relate to other error sources.

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