Astronomical evidence relating to the observed 14C increases in A.D. 774–5 and 993–4 as determined from tree rings

Abstract

A detailed study is made of celestial observations recorded in East Asian and European history around A.D. 774–5 and 993–4. These include reports of supernovae, comets, sunspots and aurorae. The aim is to attempt to provide astronomical evidence in support of the measured 14C increases in tree rings at these dates. However, the results prove to be far from convincing, leaving the physical cause of the increases still in doubt.