In early Israel, a span of 7 years was used to compute various long time cycles. One of these long time cycles was a span of 7 sets of 7 years (or 49 years). After 49 years were counted-out, a special jubilee celebration was held to announce the commencement of the jubilee year (or the 50th year).

The content of certain early-written manuscripts reveals that the jubilee year may have been celebrated in association with a system of lunar reckoning. As an example, Scroll 4QOtot is explicit in showing the routine occurrence of a lunar-cycle 'sign' in association with a count of the jubilee cycle. (The priests when revolving their courses throughout the jubilee time cycle appear to have reckoned a lunar-cycle 'sign' at a continuous frequency of each 3 years).

Astronomy makes it more certain that if the priests had observed a lunar-cycle 'sign' (at the frequency or rate of each and every 3rd year) then the priests might have been observing one of the quarter phases of the Moon. It seems that the boundary of a quarter phase of the Moon does literally revolve into almost perfect alignment with the boundary of each 3rd year (as diagrammed below).

Note: There are 4 distinct quarter phases of the Moon: 1.New phase; 2. First-quarter phase; 3. Full phase; and 4. Third-quarter phase. The quarter phases are easy to recognize on the basis of observation. At the new phase the Moon is dark and appears to be completely invisible; at full phase, the Moon is fully-illuminated and is round-shaped; and at the first quarter and at the third quarter, the Moon is half illuminated and is distinctly divided into half-parts (half-light and half-dark, or the reverse).

For the purposes of presenting a clear analysis, the lunar quarter (which completes in 7.38 days) will hereafter be referred to as a 'lunar week'.

The following chart of a 50-year cycle illustrates that the limits of each passing year can effectively be defined through a simple count of the lunar-week unit. (Note that the length of each and every year--on the average--can accurately be determined through a calendar count of 7 sets of 7 lunar weeks or 49 lunar weeks).

The diagram depicts that the jubilee time cycle (a 50-year cycle) can effectively be measured and metered out in association with a calendar comprised of lunar weeks (or lunar quarters). (Note that each calendar year--on the average--is equal to 365.2442 days. This length compares very closely with the solar circle or the tropical year--which completes in 365.2422 days).

It should be clear from the diagram that--when the rate of one lunar week every 3rd year is counted apart (or leaped) from out of the time stream--a grid of lunar weeks (2457 weeks) can be counted (repeated) in correspondence with a cycle of 50 years. Essentially, an effective calendar of lunar weeks is the inherent or automatic result of leaping one week each 3rd year from out of the time stream. (This respective rate of calendar intercalation is equivalent to 0.33333 weeks per solar year on the average).

While the available source information doesn't explicitly state that a lunar week was specially accounted for at the distance of each 3rd year, it is clear that Israelite priests probably did perpetually reckon a lunar-cycle 'sign' at this respective distance (each 3 years). This leaves some latitude in interpreting how the lunar cycle was once reckoned. For example, in reckoning the 'sign', the priests may have reckoned the lunar cycle at the resolution of the half or the whole of the lunar cycle.

The main reason for believing that the lunar cycle was once reckoned at the resolution of the quarter phase is that ancient literature is explicit in describing the priestly courses as being rotated once each week. The routinely appearing 'sign' was then accounted for right when one priestly course ended (refer to Scroll 4QOtot). The combination of this rotating schedule and the time when the 'sign' was routinely observed does not seem to allow for an alternate interpretation. Essentially, if the 'sign' was observed at the end of a 7-day cycle then it is obvious that the priests were reckoning a quarter cycle of the Moon.

For pertinent information confirming that Temple priests did once track lunar-quarters or lunar weeks, refer to the following online publications:

• Significance of the Lunar Week
• Tracking the Day-of-the-Sun

The indicated track of a lunar 'sign' points to the possibility that the priests recognized certain among the lunar weeks to be very special. The respective week which corresponded to the lunar 'sign' was apparently not counted the same as were other calendar weeks.

The following diagram is synonymous to the previous diagram in showing that primal priests may have tracked lunar phases to precisely determine the limits of a 50-year cycle:

Note that a leap week occurring each 3rd year is not shown in the following calendar chart.