What are other issues regarding intercalation of the months? What time of year can it be done? What month can be added? Can the people not being pure for the Pesach sacrifice be a consideration? How does the timing of the equinox work? Is it calculated by the autumnal equinox or by the spring equinox? Does all of Sukkot need to be in the autumn or all the days of chol hamoed or is it enough if just one day (the last) is in the autumn season? Is the equinox the last day of the previous season or the first day of the upcoming season?