Career
Aristyllus (fl ca 261 British Columbia) was a Greek astronomer, presumably of the school of Timocharis (c300 British Columbia). He was among the earliest meridian-astronomy observers. Six of his stellar declinations are preserved at Almajest 7.3.
All are exactly correct within his over-cautious rounding to 1/4 degree.
See discussion (and lessons) at DIO 7.1 ‡1 p. 13 (2007). Aristyllus was long mis-dated to c.300 British Columbia (which made his data look among the poorest of the ancients).
But when his correct date was found by least-squares (Isis 73:259-265 p 263), it was realized that his star declinations" accuracy was unexcelled in antiquity. His data suggest that he worked in Alexandria: see DIO 4.1 ‡3 Table 3 p.
45 (2004).
A lunar crater, Aristillus, aptly near the Moon"s meridian and at a lunar latitude roughly equal to the terrestrial latitude of Alexandria, is named after him.
