Shabbetai Donnolo and the Jewish Calendar: Corrigenda

A few substantial errors were unfortunately made in our article, “An Astronomical Table of Shabbetai Donnolo and the Jewish Calendar in Tenth-Century Italy” (Aleph 7, pp. 13–41), which we wish to correct here. We are grateful to the attentive readers who pointed them out to us.

1. 1. p. 33 (Table 3), first entry: read “Libra” (not Virgo).

2. 2. Pp. 37f.: the rabbinic molad of the month which Donnolo calls “Elul” occurred on Sunday, August 30, at about 4:00 a.m. (and not as indicated in the article).

3. 3. Ibid.: if Donnolo’s calendar had followed the principles of the rabbinic calendar—with the only difference that, in 946 CE, he called “Elul” the month that was reckoned in the rabbinic calendar as “Tishri”—his month of Elul would have begun on Monday, August 31 (and not on Sunday, August 30, as argued in the article). This is because the rabbinic molad of his Tishri occurred on Monday, September 28, at about 5:00 p.m.; and, following the rule of molad zaqen (see, for example, Stern, Calendar and Community, p. 192), Tishri 1 would necessarily have been postponed until Tuesday. Since in the rabbinic calendar Elul always has 29 days, Donnolo’s preceding month of Elul could only have begun on Monday, August 31, one day after the molad day. Donnolo’s month of Elul began indeed on that Monday; in this respect, he was not diverging from the rabbinic calendar.

This correction does not affect, however, the main observation that Donnolo called “Elul” the month that was reckoned in the rabbinic calendar as “Tishri,” and thus that in 946 CE his calendar diverged from the rabbinic calendar by one whole month.