Appendix I:  Chart 1  

Passover Dates, A.D. 15   36: Notes 

    Age (of moon) = amount of time from the astronomical new moon to sunset (hours : minutes). Lag1 = time 

of moonset  minus  time of sunset (in minutes) on the first evening (at sunset) after the astronomical new 

moon. Lag2 = time of moonset  minus  time of sunset (in minutes) on the second evening after the 

astronomical new moon. Times are given below in Jerusalem time (GMT + 2 hours). Day of first indisputable 

opportunity to view the crescent new moon after sunset is given in bold type, (borderline cases are underlined). 

Most probable Nisan 14 Passover dates, using observation based calendar, are also in bold. 

    This book concludes that Nisan 1 and Passover dates were determined by calculation, not observation (see 

chapter 17). An astronomical new moon date prior to solar transit (noon sun time) would place Nisan 1 on the 

same day as the new moon date; if after solar transit, Nisan 1 would begin the next day. The first date in the 

column for Nisan 14 range is the one accepted in this book's conclusions. 

    Jewish leap years were determined in ancient times by three factors: the date for the  Spring Equinox, the 

maturity of the grain harvest, the maturity of the fruit trees harvest.

1241

 Since we can only determine the date of 

the Spring Equinox, we cannot be certain which years were leap years. The decision as to which years would 

be leap years, in ancient times, was a human decision made by the Jewish religious leaders. For this reason, in 

some years two sets of dates are given in Chart 1, to take into account the possibility of a Jewish leap year. 

    Nisan 14 was not allowed to fall on a Thursday (to avoid conflict between Nisan 15 and Friday, the 

preparation day of the Sabbath). In such a case, Nisan 1 would be delayed a day, from Friday to Saturday, and 

Nisan 14 would fall on a Friday instead of a Thursday. The above ranges for Nisan 1 and Nisan 14 take this 

consideration into account. For this reason, there should not be any Friday Nisan 1 dates or Thursday Nisan 

14 dates in Chart 1. 

    New moon and  Spring Equinox dates and times taken from  RedShift 3  astronomy software. New moon 

dates were checked against data from NASA web site. Days of the week taken from Universal Calendar 

Calculator 

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