Comparison of Equations for Meridional Distance from the Equator

Abstract

Three equations for meridional distance from the equator are compared. Accuracies, advantages and disadvantages are discussed. Conventional equation with higher terms has enough accuracy and slow convergence. Bessel’s simple equation is very easy for computer programming and has the fastest convergence and the fastest calculation speed. An analytic equation derived from elliptic integrals is easy for programming and has fast convergence and the highest accuracy.