| SN 1917A | |
| Event Type: | Supernova |
| Start Time: | 19 July 1917 |
| Distance: | 6.8Mpc |
| Peak: | 13.60 |
SN 1917A is a supernova event in the Fireworks Galaxy (NGC 6946), positioned west and south of the galactic core. Discovered by American optician George Willis Ritchey on 19 July 1917, it reached a peak visual magnitude of 13.6. Based on a poor quality photographic spectrum taken at least a month after peak light by F. G. Pease and Ritchey, it was identified as a type II core-collapse supernova.
A 2018 analysis of the surrounding stellar population by B. F. Williams suggests the progenitor star was most likely 13 million years old with 15 times the mass of the Sun . B. Koplitz and associates in 2021 inferred a progenitor mass estimate of . A 2020 search for light echoes from the supernova was unsuccessful.