The official, church-equinox in the Gregorian calendar is on March 21. The official equinox in the Julian calendar is also on March 21, which at present corresponds to April 3 Gregorian.

Besides this 13-day difference in the solar calendar, the lunar calendars are out of phase as well. The Gregorian lunar calendar approximates the age of the moon fairly well--today is the 11th day of the moon in the Gregorian lunar calendar--while the Julian lunar calendar is about 4 days behind the moon. Today, September 10, 2017, is only the 7th day of the moon according to the Julian lunar calendar.