CTB 1 is also circulating on the Internet as PN Abell 85. In his list of planetary nebulae, G.O. Abell cautiously noted that it could also be an SNR. CTB 1 (SNR G116.9+00.1) is basically a round ring, spatially a sphere. The ring structure is non-thermal both optically and in the radio range, but inside a hot plasma with thermal X-rays is registered. The distance is ~8800 ly, which gives a true diameter of 87 ly.

The star that explodes as a supernova ends up as a neutron star (pulsar). But such pulsars were not found in all supernova remnants. Space exploration by satellites therefore aimed at shorter wavelengths than optical ones. More than 200 gamma pulsars have now been discovered. In addition, the gamma pulsar PSR J0002+6216, among others, was also detected in X-ray wavelengths. It is only 28' from the geometric center of CTB 1. In order to confirm that this pulsar belongs to CTB 1, radio astronomical studies of PSR J0002+6216 were carried out in August 2017 using the Very Large Array (VLA). F.K. Schinzel et al. (2019) found that the pulsar is moving quickly away from CTB 1. A back calculation of the trajectory showed that PSR J0002+6216 could have passed through the geometric center of CTB 1 10-20,000 years ago, so that would have been the time of the explosion. What is remarkable is that the pulsar leaves a tail behind it as it moves through the interstellar medium - like a comet. However, the pulsar and tail cannot be detected optically.

In the upper right corner of the image, two small, round HII regions can be seen. The brighter one with a size of 7.8' is [GS55] 281 = SIM 104 = Sh2-168 = LBN 568. The name SIM 104 comes from the fact that this nebula was identified as a radio source at the Simeis Observatory in Crimea in the 1950s. In the nebula, the 11.6 mag bright star LS I +60°50 with its spectral type B0V provides sufficient excitation energy. Directly below, much darker, is the HII region Sh2-169 with a size of 8.9'. Inside, the 10 mag bright B0 star BD+59°2786 with the spectral type B0 provides just enough excitation for the nebula emission.

At the bottom left of the image you can see parts of the HII region Du 62. This name goes back to the French astronomer R. Dubout-Crillon: HII regions of the Northern Milky Way: medium large field photographic atlas and catalogue; Astron. Astrophys. Suppl. Ser. 25, 25-54 (1976).

At bottom right of the image: The star cluster Berkeley 1. The inconspicuous cluster sits in an irregular, diffuse HII region with the catalogue number Du 61.

At the left edge of the image you can clearly see an arched, fibrous strand of nebula. It extends from top to bottom (west-east direction). Fibers or filaments are always typical of supernova remnants. This is the southern edge of the SNR G117.4+1.5. It was discovered in 2005. So we have two optically clearly visible supernova remnants in the image - great!

Source (german):
https://forum.astronomie.de/threads/46-woche-ctb-1-ein-supernovarest-im-sternbild-cassiopeia.334477/