Odalan is a commemoration ceremony of a temple. It’s like a birthday of a temple. But not like international calendar which has 365 days in a year, Bali calendar has different system of calculation. It based on oton which recurs in 210 days instead of 365 days as in international calendar. So odalan recurs in 210 days however there is some temple which use another Bali calendar system using sasih (rotation of the moon) calculation and it occurs every year as (almost similar like) international calendar.