the strong indications that Cas A is a supernova remnant, no clear historical mention of the event has been found, although there is some evidence that the English astronomer John Flamsteed may have witnessed it in 1680. The lack of an eyewitness is surprising, since earlier than that the great European astronomers Tycho Brahe and Johannes Kepler recorded other supernovae. Even the assiduous Chinese court astronomers, whose predecessors had made such precise measurements of the Crab Nebula in 1054­1056, did not mention Cas A, despite the fact that it was probably even brighter than the Crab supernova.
