Azimuth data base errors - Theory and analysis

Astronomic azimuth and transfer angle measurement data obtained during a three year period at the Advanced Inertial Test Laboratory (AITL) were analyzed to gain an understanding of the accuracy of the results. The objectives of this investigation were to determine the causes of the errors in astronomic azimuth observations, as well as the reasons for the variations in the value of the azimuth data base. The current accuracy requirement of + or - 0.6 arcsec and the desired accuracy of + or - 0.4 arcsec can presently be obtained if certain precautions are followed. Higher accuracy requirements can be met only when following the recommendations given for the modifications of the observing instruments and methodologies, and when monitoring the movements of the Porro prism support on a continuous basis. Personal errors in azimuth observations were derived from observations and applied to the data to test the validity of their determination.