BRLANTIDA

"The link between past and present is even more crucial for Cassiopeia A, which exploded sometime after 1660"

"They found evidence for several sets of light echoes rippling across patches of dust in the northern Milky Way. The echoes appear to originate from two distinct locations in the sky, one corresponding to the known position of Tycho's supernova and the other to Cassiopeia A, both of which are now just clouds of ionised material. [...] The discoveries are more than an astronomical curiosity. The echoes of Tycho's supernova should verify exactly what type of explosion caused it and help piece together the sequence of events that led to the glowing wreath of gas left over at the same place today.

The link between past and present is even more crucial for Cassiopeia A, which exploded sometime after 1660 but went unrecorded, presumably because its brilliant flash was obscured by dust. Its remnant was first detected by British radio astronomers in 1947."

Semeniuk, I. Light echoes show Tycho's supernova as it looked four hundred years ago. New Scientist. 1/26/2008, Vol. 197 Issue 2640, p16.