Common mistakes in celestial navigation — what are they?

Failure to Account for Atmospheric Refraction

Atmospheric refraction can cause errors of up to 1 degree in altitude readings, which can result in navigation errors of several miles. To compensate, navigators can use correction tables or consult a nautical almanac to determine the amount of refraction for the specific time of day and location. This correction should be applied to the observed altitude of the celestial body, rather than the calculated altitude.

Incorrect Use of Altitude for Time of Year and Location

The altitude of the sun or stars varies with the time of year and location due to the Earth’s tilt and rotation. For example, the sun’s altitude at noon in the northern hemisphere during the summer months is 90 degrees minus the latitude, while in the winter months it is 90 degrees minus the latitude and the sun’s declination. Navigators must take into account these variations when using celestial navigation charts and tables.

Neglecting Latitude and Longitude Effects on Navigation Charts

Celestial navigation charts and tables are typically based on a specific grid system that assumes a particular latitude and longitude. Failure to account for the navigator’s actual latitude and longitude can result in errors of several miles. To compensate, navigators can use a chart correction table or consult a nautical almanac to determine the corrections needed for their specific location.