Abstract:Current research on digital zenith camera is mainly focused on the positioning application, so a method of calculating the angle between the x axis and the north direction of the CCD coordinate system is studied.Based on the calculation of the astronomical coordinates of the rotating axis of the zenith telescope obtained from the two stars in the symmetric position, and calculating the true value of the position of the measuring station, the corresponding tangent of the tangent plane coordinate system is obtained.With the angle of 2-axis inclinometer measurement, we calculate the inclinometer X-sensitive axis azimuth angle, and using the least squares algorithm, calculate the directional inclinometer angle.Finally,we calculate the CCD x axis azimuth, directionally.The experimental results show that the digital zenith camera in a work cycle of data calculation, gets the azimuth angle of the standard deviation of σ=3.06′.Thus CCD x axis azimuth meet the requirements of 3σ, can achieve the purpose of orientation.