issue with the superior epoch was its tedious computation. It not only didn't help with the almanac making but also became an obstacle to the further improvement of almanacs.</p><p>As the measurement precision continued to improve, values of the tropical year and synodic month had to be approximated by more complicated fractions. That is, values of T, U and A became large, resulting in large values of N. A large value of N was inconvenient for almanac calculation, so people tried to limit N to be less than 