Abstract:

According to maritime astronomy positioning principle, the special nature of the sun can be used for astronomical positioning. When the sun transits, the green semicircle angle is equal to observer’s longitude. According to the law of the sun’s apparent motion, when one uses a sextant, it is difficult to determine the transit time of the sun, and the longitude error will be introduced. In order to solve this problem, combined with data fitting techniques, first the feasibility of fitting solar altitude curve is discussed and demonstrated, then a celestial autonomous positioning method is proposed that doesn’t need projected position. Experimental results showed that the positioning cycle with the algorithm is short, it is simple to carry out and helps to reduce accidental errors. Under skilled observation level, maximum error of latitude and longitude are 0.8 and 2.5, which can fully meet the needs of the general maritime activities.