Hipparchus confirmed this value for the lunation length. Ptolemy accepted and used it, as mentioned above. Hillel II first used it in the Hebrew calendar, and it has been used for that purpose ever since. The existing evidence makes it difficult to put Kidinnu at a time and place. Schnabel placed Kidinnu in Sippar, but Otto E. Neugebauer showed that Schnabel based this conclusion on a misreading of the cuneiform tablet. Classical sources like Strabo mention different "schools" and "doctrines" followed in different places (Babylon, Borsippa, Sippar, Uruk). System A and B have been used contemporaneously, and tablets for both systems have been found in both Babylon and Uruk. Tablets based on System B, associated with Kidinnu, have been found mostly in Uruk, but the earlier tablets came predominantly from Babylon. The oldest preserved tablet using System B comes from Babylon and dates from 258 to 257 BC. This is in the Seleucid era, but it is plausible that the traditional Chaldean astronomical systems had been developed before the Hellenistic period. The Alexander chronicle mentioned above suggests that the famous astronomer Kidinnu died in Babylon in 330 BC, if it refers to the same Kidinnu who was mentioned on the ephemeris tablets centuries later. Legacy The crater Kidinnu on the Moon is named after him. References Otto E. Neugebauer: A History of Ancient Mathematical Astronomy Part One II Intr. 3.1 (pp. 354–357), Part Two IV A 4, 3A (p. 602) and IV A 4, 4A (pp. 610–612). Springer, Heidelberg 1975 (reprinted 2004). Otto E. Neugebauer: Astronomical Cuneiform Texts. 3 volumes. London: 1956; 2nd edition, New York: Springer, 1983. (Commonly abbreviated as ACT): Part I pp. 12,13. Herman Hunger and David Pingree: Astral Sciences in Mesopotamia pp. 183–188, 199–200, 200–201, 214–15, 219, 221, 236, 239. Brill, Leiden 1999. External links Kidinnu, the Chaldaeans, and Babylonian astronomy Astronomical Artefacts and Portraits, etc: Franz Xaver Kugler SJ Year of birth unknown 330 BC deaths Babylonian astronomers People from the Achaemenid Empire 4th-century BC people 4th-century BC astronomers