Abstract: Precise source localization in passive sonar with linear, horizontal passive array and matched beam processing algorithms requires, among others, accurate determination of the fixed array position and orientation. Geographical coordinates of the array can be evaluated quite simple with precise GPS receiver. Especially important problem is then the accurate determination of the array orientation. It is not a trivial problem and simple compass measurements may produce precision troubles. At the paper a method that compares the known trajectory of a moving acoustic source and its bearings computed with the array system software is developed. The method is based on minimizing the function of square error between the true and candidate-estimated target positions. Another interesting feature of proposed algorithm is the possibility of optimizing the error function with respect to parameters that model in an assumed way signal prapagation characteristics.