19:2719:27, 12 May 2020diffhist−6
m
Tropical year
tropical year is an astronomical term which developed in the northern hemisphere so its vernal equinox is the March equinox
20:2620:26, 29 April 2020diffhist−257
Anatolius of Laodicea
The Alexandrian lunar cycle was mature before 325 because it was used in 311-368. The only "uncertain" dates are by other computists who either did not not understand the Alexandrian computus or objected to one or more of its dates, like Victorius of Aquitaine.