This is a widefield view of the galaxy, M100, directly left of the center of the picture - captured with an amateur telescope in 2025.
After the discovery of M100 by Méchain,Charles Messier made observations of the galaxy depicting it as a nebula without astar. He pointed out that it was difficult[7] to recognize thenebula because of its faintness.William Herschel was able to identify a bright cluster of stars[7] within the "nebula" during his observations. His sonJohn expanded the findings in 1833. With the advent of better telescopes, John Herschel was able to see a round, brighter galaxy; however, he also mentioned that it was barely visible through clouds.William Henry Smyth[7] extended the studies of M100, detailing it as a pearly white nebula and pointing out diffuse spots.
As usual on spiral galaxies of the Virgo Cluster, in the rest of the disk both star formation[13] andneutral hydrogen, of which M100 is deficient compared to isolated spiral galaxies of similarHubble type,[14] are truncated within the galaxy's disk, which is caused by interactions with theintracluster medium of Virgo.
Heber Curtis discoveredSN 1914A (type unknown, mag. 15.7)[5][18] on 2 March 1914, at 24"E and 111"S from the galaxy's nucleus.[15][17]
Milton Humason, with observations from early to mid 1960,[b] discoveredSN 1959E (Type I, mag. 17.5),[5][19] located 58"E and 21"S from the galaxy's nucleus.[20]
On 15 April 1979, amateur astronomer Gus Johnson discoveredSN 1979C, the firstType II supernova found in the M100 galaxy. However, the star faded quickly, and later observations from x-ray to radio wavelengths revealed its remnant.[5][21][22]
SN 2006X (Type Ia, mag. 15.3) was discovered by Shoji Suzuki and Marco Migliardi on 7 February 2006, two weeks before fading to magnitude 17.[5][23][24][25]
Jaroslaw Grzegorzek discoveredSN 2019ehk (TypeIb, mag. 16.5) on 29 April 2019. The supernova reached a peak magnitude of approximately 15.8.[26]
SN 2020oi (TypeIc, mag. 17.28) was discovered byAutomatic Learning for the Rapid Classification of Events (ALeRCE) on 7 January 2020.[5][27][28]
^Wozniak, H.; Friedli, D.; Martinet, L.; Pfenniger, D. (1999). "Double-barred starburst galaxies viewed by ISOCAM".The Universe as Seen by ISO.427: 989.Bibcode:1999ESASP.427..989W.
^Sakamoto, Kazushi; Okumura, Sachiko; Minezaki, Takeo; Kobayashi, Yukiyasu; et al. (1995). "Bar-Driven Gas Structure and Star Formation in the Center of M100".The Astronomical Journal.110 (3): 2075.Bibcode:1995AJ....110.2075S.doi:10.1086/117670.
