had their own epochs separate from the superior epoch. The adopted synodic periods were much more accurate than the previous almanacs. H&#233; agreed with D&#249; Y&#249; that astronomical constants should be determined by observations only. However, H&#233;'s approach received criticisms and subsequent almanac makers didn't follow his approach.</p><p>From the example above, we see that as long as the number of years N from the superior epoch is large, it's easier to approximate the measurement values to ma