Qumran calendrical texts

There are about twenty different texts from Qumran that deal with a lunar phase calendar.^[1] They are mainly very fragmentary, so the calendar is not completely understood. However, it is significantly different from the Babylonian lunar calendar which evolved into the 354-day Hebrew calendar as known today. The scrolls calendar divided the year into four quarters and recorded the feast days of the community. Feasts were fixed to moon phases and so occurred on different days from those indicated in the Babylonian-based calendar. Many of the texts are rosters of weekly shifts or courses of temple service for the twenty-four priestly families, known as Mishmarot.^[2]

There is some ambiguity as to whether the four cardinal days were at the beginning of the months or at the end, but the clearest calendar attestations give a year of four seasons, each having three months of 30, 30, and 31 days with the cardinal day the extra day at the end, for a total of 91 days, or exactly 13 weeks. Each season started on the 4th day of the week (yom Revii ; יוֹם רְבִיעִי), every year.^[3]

The writings often discuss the moon, but the calendar was not based on the movement of the moon any more than indications of the phases of the moon on a modern western calendar indicate that that is a lunar calendar. Recent analysis of one of the last scrolls remaining to be deciphered has revealed it relates to this calendar and that the sect used the word tekufah to identify each of the four special days marking the transitions between the seasons.^[4]