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Declinations in the Almagest: accuracy, epoch, and observers

Brandt, John C.; Zimmer, Peter; Jones, Patricia B.

Almagest declinations attributed to Timocharis, Aristyllos, Hipparchus, and Ptolemy are investigated through comparisons of the reported declinations with the declinations computed from modern positions translated to the earlier epochs. Consistent results indicate an observational accuracy of ≈ 0.1° and epochs of: Timocharis, c. 298 BC; Aristyllos…