Abstract
Vector analysis is used to determine the quantitative error in angle calibration using autoeollimators. This error is caused by tilt in the mount upon which the artifact is placed. For tilt angles that are less than 1°, the error can be simplified to be the product of a eoeffieient and three terms. The three terms are: (1) the square of the tilt, (2) the sine of the artifact's nominal angle, and (3) the eosine of the artifact's nominal angle plus two times the artifact's position angle. It is shown that the error can be eliminated by placing the artifact at designated periodic positions.