Determining the Absolute Parameters of the Meridian Circle by Observing the Prime Vertical (Ⅶ) Curvature Correction of the Determination Value of An Apparent Zenith Distance in the Prime Vertical Direction

In this paper, the expression, accurate to the quatratic temas, of the curvature correction of the determination value of a zenith distance in the prime vertical direction is strictly derived by means of the expansion of a trigonometric function in series. Although the result obtained by this method can only be accurate to the quatratic terms, it is more accurate than that obtained by the approximate derivation method of the plane projection of the field of view.