Sun Altitude - Refraction Correction

Refraction correction for a sextant sun altitude at standard atmospheric conditions - Bennett empirical formula.

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This calculator requires JavaScript to compute its result. The formula, symbols, and regulatory sources are shown in the Formula section below.

Formula, assumptions, and limits

R = \frac{1}{\tan(h_a + 7.31/(h_a + 4.4))}

Symbol	Meaning	Unit
$h_a$	Apparent altitude	deg

Source: Bennett G.G. - J. Nav. 1982; Bowditch Pub.9 Ch.20

Refraction correction for a sextant sun altitude at standard atmospheric conditions - Bennett empirical formula.