Accuracy of medieval Chinese and Middle-Eastern timings of eclipses.

Analysis of 111 Chinese timings of solar and lunar eclipses in the period AD 434–1280 and of 56 Middle-Eastern timings in AD 829–1020 reveals that their accuracy approached the limiting resolution of their clock systems. The Chinese accuracy improved progressively over the period of observation, with the standard deviation reducing from approximately 18 minutes round about AD 600 to 7 minutes circa AD 1200. The Middle-Eastern timings have a standard deviation of 5 minutes around AD 950. [ABSTRACT FROM AUTHOR]