Vol. 552
In section 1. Letters to the Editor

The AD775 cosmic event revisited: the Sun is to blame

by I.G. Usoskin, B. Kromer, F. Ludlow, J. Beer, M. Friedrich, G. A. Kovaltsov, S. K. Solanki, and L. Wacker, A&A 552, L3

Recently there have been intense discussions regarding a very strong cosmic event in AD 775 close to the Earth, such as a close supernova or gamma-ray burst, a hypothesis that was based on radiocarbon data. This new study investigates a range of isotope data and concludes that the above speculations on exotic astrophysical events was premature. The improved isotope analysis also shows an enhancement of the cosmic ray flux at the time, but only within the normal variations we know to originate from solar activity. Thus, there seems to be little evidence for an abnormal astronomical event in AD 775.