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Paper: Astronomy of Maimonides and Its Arabic Sources
Volume: 409, Cosmology Across Cultures
Page: 188
Authors: Belenkiy, A.
Abstract: In this paper, we analyze the fact discovered by Otto Neugebauer in a 1949 paper explaining why the mean lunisolar conjunction set by Maimonides in his Code of Jewish Law, Mishneh Torah, differs from the molad (Jewish calendar conjunction) by 1 hour and 17 minutes. We also address Neugebauer’s fundamental question of whether the molad is a mean conjunction. This problem leads us to a further examination of Maimonides’ sources on the one hand and to a clarification of the notion of molad on the other. First we conjecture that a difference of circa 50 minutes between the epochs of Maimonides and alBattânî came from a geographical manuscript that was different than al-Battânî’s treatise, which was translated by Carlo Nallino in 1903 and which quoted an unreasonably high longitude for Raqqa (the location of al-Battânî’s observations) compared with Jerusalem’s longitude. Second, examination of a time difference between al-Battânî’s mean lunisolar conjunction and the molad shows an additional circa 27-minute difference. This proves that the interval of 1 hour and 17 minutes between Maimonides’ conjunction and the molad consists of only two parts and does not require the additional assumptions made by previous researchers. We conclude by reiterating that molad is Ptolemaic mean lunisolar conjunction while Maimonides used al-Battânî’s mean lunisolar conjunction.
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