In this image I merged together all the signal that I managed to get from the Pinwheel Galaxy (M101), deriving from the sessions at the beginning and end of 2023 and beginning of 2024, for a total of over 50h between broadband and narrow band imaging. Such an important integration allowed me to bring out very faint details of this galaxy, which I had never noticed before and which I only found during the development of this photo in other images, such as the faint spiral arms at the bottom and to the left with respect to the galactic center.
When I shooted M101 early last year, the Supernova SN 2023ixf (discovered on May 19, 2023) had not yet exploded. Instead, during the most recent shots it was clearly visible and, in fact, it appears in my photo where it shines at magnitude 16 (more or less). You can seen the Supernova highlighted with mouseover.

The Pinwheel Galaxy (also known as Messier 101, M101 or NGC 5457) is a face-on spiral galaxy 21 million light-years away from Earth in the constellation Ursa Major. It was discovered by Pierre Méchain in 1781 and was communicated that year to Charles Messier, who verified its position for inclusion in the Messier Catalogue as one of its final entries.
Messier 101 is estimated to contain 1 trillion stars and an unusually high number of H II regions, where new stars form. Nine of these were bright enough to get their own designations in the New General Catalogue: NGC 5447, NGC 5449, NGC 5450, NGC 5451, NGC 5453, NGC 5455, NGC 5461, NGC 5462 e NGC 5471 (open Astrobin link to see them).
With a linear extension of 170000 light years, the Pinwheel Galaxy is about 70 percent larger than the Milky Way. The estimated mass of M101’s disk is about 100 billion solar masses, while its small central bulge has a mass 3 billion times that of the Sun. The galaxy has an absolute magnitude of -21.6, corresponding to a luminosity of 30 billion Suns. The galaxy does not appear to have a supermassive black hole at its centre.
M101 has five prominent companions: NGC 5204, NGC 5474, NGC 5477, NGC 5585 and Holmberg IV. Gravitational interaction with these galaxies is suspected to have triggered the formation of the grand design structure in M101 and distorted NGC 5474. The Pinwheel Galaxy and its companions form the M101 Group, a group of at least nine galaxies centred on M101. In addition to the Pinwheel’s companions, probable group members include the galaxies NGC 5238, UGC 8508 and UGC 9405.