SN 1572

SN 1572 (also Tycho's Star, Tycho's Nova, or Tycho's Supernova), or B Cassiopeiae (B Cas), was a supernova of Type Ia in the constellationCassiopeia, one of eight supernovae visible to the naked eye in historical records. It appeared in early November 1572 and was independently discovered by many individuals.

Its supernova remnant has been observed optically but was first detected at radio wavelengths. It is often known as 3C 10, a radio-source designation, although increasingly as Tycho's supernova remnant.