Research suggests a medieval chronicle may have recorded a sighting of a recurrent nova star, T CrB, brightening in 1217. The description matches T CrB's behavior, ruling out other possibilities such as a supernova or comet. If the star follows its previous pattern, it should brighten again in 2024.
https://phys.org/news/2023-09-medieval-manuscript-impending-recurrent-nova.html