Determining Ship’s Position by the Celestial Altitude Difference Using the Least Squares Method

Nguyen Thai Duong, Luong Tu Nam


Although obtaining the position of a ship by a celestial method is not very accurate by today’s standards, it is an independent method, especially for offshore navigation. In modern navigation, a ship will typically be equipped with two electronic chart display and information systems (ECDISs). Thus, celestial ship positioning will be a primary backup method. In some special situations, the requirement for the accuracy of the ship’s position by a celestial method is not as high as when modern navigational methods are being used. By traditional methods, a ship’s officers would observe, measure, calculate, and plot the lines of position on a nautical chart to determine the ship’s position. Recently, some studies have proposed frameworks to solve the celestial problem in determining the longitude and latitude of the ship using appropriate algorithms. Each method has its own advantages, disadvantages, and certain applicability in practice. This paper proposes a new method to fix a ship’s position by calculating the least squares of the altitude variations of celestial bodies. A program for calculating a ship’s position with high reliability and applicability based on the new algorithm was also constructed, demonstrating its effectiveness in practice.



Keywords: ship positioning, celestial navigation, altitude variation, least squares method.





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