Abstract
Although the ship's position by the celestial navigation fix method is not very accurate, it is an independent method, especially when navigating on the open sea. In the modern maritime, the ship's position by celestial altitude is the main backup method because the ship will be equipped with two the Electronic Chart Display and Information Systems. For that, the requirement for the accuracy of the astronomical position will not be as strict as used navigation in previous navigational methods. In the traditional navigational method, the officer of watch must measure, calculate, and manipulate astronomical position lines to determine the ship's position on the chart. Currently, there have been several studies that used appropriate algorithms for determining the ship's position by the astronomical method. However, each method has certain advantages and disadvantages and certain applicability in practice. This research proposes a method to find the minimum squared value of the difference of the celestial altitude to determine the ship's position with the most probability.