One of only five supernovae in the Milky Way confidently identified in pre-telescopic records,[1] it appeared in the constellation Cassiopeia and was visible and motionless against the fixed stars for 185 days.

[2] Pa 30 was discovered in 2013 by American amateur astronomer Dana Patchick while searching for planetary nebulae in WISE infrared data.

X-ray spectroscopy studies of the shell also revealed a very hot nebula containing carbon-burning ashes which can only be produced in a supernova.

[11] The extreme properties of the central star are being powered by the residual radioactive decay of 56Ni, where the usual half-life of 6.0 days from electron capture is increased to many centuries due to the nickel being completely ionized.

[13] This is in contrast to the Crab pulsar, known to be the remnant of the SN 1054 supernova in the year 1054, which has lost two-thirds of its rotational energy in essentially the same span of time.

[15] [16] Most directly, the proper motion of the expanding shell of 3C 58 has been measured three times, resulting in a distance-independent estimated age of around 3500 years.

Age estimates involving the remnant's energy and the swept-up mass are both not useful due to large uncertainties with the distance as well as the presumed energetics and densities.

The possible sky position of the 1181 supernova has been revised to include additional information on the proximity of the "guest star" to adjacent Chinese constellations, resulting in a greatly smaller error region.