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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…

Magnitude systems in old star catalogues

Yamaoka, Hitoshi; Fujiwara, Tomoko

The current system of stellar magnitudes originally introduced by Hipparchus was strictly defined by Norman Pogson in 1856. He based his system on Ptolemy's star catalogue, the Almagest, recorded in about AD137, and defined the magnitude-intensity relationship on a logarithmic scale.

Stellar magnitudes observed with the naked eye recorded in …