 He did the same procedure with Timocharis' data (Evans 1998, p. 251).Observations such as these eclipses, incidentally, are the main source of data about when Hipparchus worked, since other biographical information about him is minimal.The lunar eclipses he observed, for instance, took place on 21 April 146 BC, and 21 March 135 BC (Toomer 1984, p. 135 n. 14).