Cometary records revise Eastern Mediterranean chronology around 1240 CE

Eirene Laskarina, empress of John III Batatzes the exiled Byzantine Empire Nicaea (1204--1261 CE), was an important Eastern Mediterranean figure in first half thirteenth century. We reassess date Eirene's death, which has been variously dated between late 1239 and 1241, with understanding that narrowing range this event occurred contributes much to political situation area around 1240. George Akropolites, a famous official Empire, gives account connects death comet appeared "six months earlier", thus pointing two candidates were visible from one recorded on "3 June 1239" other "31 January 1240". Recent historians prefer former, based historical circumstances without critical assessment records. revisit records reveal candidate not comet. On hand, candidate, sighted 1240", comet, as supported by multiple regions, is also good fit Akropolites's narrative. Therefore, we conclude died six after seen 31 1240, places her summer Given crucial for determining some contemporary events across Mediterranean, our results offer solid basis further research thirteenth-century Mediterranean.