Deer Lick Group
About this image
NGC 7331 is a beautiful spiral galaxy in the constellation Pegasus, approximately 45 million light-years from Earth. Also known as Caldwell 30, it was discovered by William Herschel in 1784 and is often compared with our own Milky Way because of similarities in its size, mass and spiral structure.
In September 2026, NGC 7331 became particularly interesting with the appearance of SN 2026aaiv, a Type Ia supernova. It was first detected by the ATLAS survey on 1 September 2026, at a magnitude of approximately 17.3.
Type Ia supernovae are caused by the thermonuclear destruction of a white dwarf star. For a short period, the resulting explosion can become extraordinarily luminous, allowing it to be detected across millions of light-years.
What makes imaging SN 2026aaiv particularly fascinating is the distance involved. NGC 7331 is around 45 million light-years away, so the light I captured left that galaxy roughly 45 million years ago. The explosion we are seeing today therefore happened when Earth looked very different from the world we know now.
I actually noticed the supernova independently while processing my own image of NGC 7331. For a short while I thought I might have discovered it, before finding that ATLAS had beaten me to it by several days.
Even so, there is something quite remarkable about looking at your own astronomical image, spotting a star that should not be there, and realising that you are recording the light from a stellar explosion that occurred around 45 million years ago.
Annotated image
Image details
| Object type | galaxy |
|---|---|
| Catalogue | NGC 7331, PGC 69327, C 30 – NGC 7331 – PGC 69327 – UGC 12113 |
| Constellation | Pegasus (Peg) |
| Observed | 2026 Sep 11 – 22:00 UTC |
| Location | Portsmouth, UK |
| Moon | New Moon – 0% illuminated – age 0.1 days |
| WordPress categories | Galaxies, Supernova |
Equipment
| Telescope | Skywatcher 127 Mak |
|---|---|
| Camera | ZWO ASI2600MC Pro |
| Mount | Juwei 17 |
| Filter | None |
| Focal length | 1500mm |
| F-ratio | f/11 |
| Pixel scale | 0.52 arcsec/pixel |
Acquisition
| Exposure | 346 x 60s |
|---|---|
| Gain | 100 |
| Guiding RMS | 0.9 |
Observation notes
I thought I’d discovered a supernova in NGC 7331. Turns out SN 2026aaiv had already been discovered by the ATLAS survey on 1 September 2026.
Still I captured it myself. NGC 7331 is around 46 million light-years away, meaning the light from this explosion began its journey towards us roughly 46 million years ago and only now reached my telescope. Pretty amazing!
Processing notes
Using APP and Pixinsight. Normal processing flow.
Posted from CityAstroLog.