SN 1917A is a supernova event in the Fireworks Galaxy (NGC 6946),[2] positioned 37″ west and 105″ south of the galactic core.[1] Discovered by American optician George Willis Ritchey on 19 July 1917, it reached a peak visual magnitude of 13.6.[1] Based on a poor quality[5]
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.[6][7]
A 2018 analysis of the surrounding stellar population by B. F. Williams suggests the progenitor star was most likely 13+13 −1 million years old with 15+1 −5 times the mass of the Sun (M☉).[3] B. Koplitz and associates in 2021 inferred a progenitor mass estimate of 9.3+16.7 −0.7M☉.[8] A 2020 search for light echoes from the supernova was unsuccessful.[9]
References
^ abcdefghBarbon, R.; et al. (2008), "Asiago Supernova Catalogue", CDS/ADC Collection of Electronic Catalogues, vol. 1, Bibcode:2008yCat....1.2024B.