On the calendar based on the Abiv Barley and visible sighting of the New Moon in Israel, the 25th day of the 9th month is the same day if you use potential visibility, but is one day later if you use actual visibility with 30-day maximum.
When the holiday is a traditional holiday and not a moed (appointed time) or miqra kodesh (commanded assembly), our congregation celebrates on the traditional calendar dates except for the years when the two calendars are a month apart. In those years we follow the Abiv calendar dates for the traditional holidays as well so that Purim does not conflict with Pesach (Passover).
