Aristyllus


Aristyllus was a Greek astronomer, presumably of the school of Timocharis. 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 at ‡1 p. 13.
Aristyllus was long mis-dated to c. 300 BC ; but when his correct date was found by least-squares, it was that his star declinations' accuracy was unexcelled in antiquity. His data suggest that he worked in Alexandria: see ‡3 Table 3 p. 45.
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.