Which limitation complicated longitude determination despite Harrison's chronometer during 18th-century voyages?

💡 Explanation

When celestial observations calculated local time, atmospheric refraction bending starlight introduced errors because refraction varies with temperature and air pressure causing imprecision in determining the angle to the celestial object at the horizon. Therefore atmospheric refraction variability limited accuracy, rather than deviation, instability, or imperfections, which present different navigational challenges.

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