Supernova SN 2025rbs in the NGC 7331 spiral galaxy: an image – 16 July 2025.
We observed supernova SN 2025rbs in the stunning galaxy NGC 7331, two days after its discovery: here we present our image.
Supernova SN 2025rbs in the NGC 7331 galaxy: 16 July 2025.
The image above comes from the average of 9, 300-second unfiltered exposures, remotely taken with the “Elena” (PlaneWave 17″ + Paramount MEII + SBIG STL-6303E) robotic unit available as part of the Virtual Telescope Project and installed in Manciano, Italy. The supernova is indicated by an arrow in the upper left insert.
We estimated SN 2025rbs as bright as mag. 14.0 (R-mags for the reference stars from the Gaia DR2 star catalogue), likely around its peak. SN 2025rbs was discovered on 14 July 2025 and it is a type Ia supernova.
NGC 7331, the host galaxy, is an important, outstanding spiral located about 40 million light-years away in the constellation Pegasus. Discovered by William Herschel in 1784, it is often referred to as a “twin” of the Milky Way due to its similar size, structure, and orientation. Its disk is inclined about 75° from our line of sight, offering a dramatic view of its dust lanes and spiral arms. The central bulge is prominent and hosts a supermassive black hole. With an apparent magnitude of 10.4, it is a frequent target for astrophotography.
Just a few arcminutes away lies an intriguing group of smaller galaxies often called the “Deer Lick Group”, although they are not physically associated with NGC 7331. These galaxies — including NGC 7335, NGC 7336, NGC 7337, and NGC 7340 — appear close in the sky but are actually much farther away, at distances exceeding 300 million light-years. Their apparent proximity to NGC 7331 is a mere line-of-sight coincidence.
Despite this, the visual contrast between NGC 7331 and its background companions makes this region of the sky particularly appealing. The large, detailed spiral stands out against the delicate, fainter smudges of the distant galaxies, offering a natural tableau that illustrates the vast scales of the universe.
Among other supernovae in the same galaxy over the recent years, in 2013 we also observed SN 2013bu
We will keep an eye on this supernova on the next months.
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