NGC7331 is a unbarred galaxy Type SA(s)b edge-on spiral 40 million light-years from Earth in constellation Pegasus. NGC7331’s apparent magnitude is 10.4 and was discovered by William Hershel in 1784. NGC7331 is a foreground galaxy in a visual group of background galaxies, but not gravitational associated with them. This visual group of galaxies is known as Deer Lick Group. The four background galaxies are affectionately referred to as “fleas”.

The galaxy appears similar in size and structure to the Milky Way and is sometimes referred to as “the Milky Way’s twin”. However, discoveries in the 2000s regarding the structure of the Milky Way may call this similarity into doubt, particularly because the latter is now believed to be a barred spiral, compared to the unbarred status of NGC7331.

In spiral galaxies the central bulge typically co-rotates with the disk but the bulge in the galaxy NGC7331 is rotating in the opposite direction to the rest of the disk. In both visible light and infrared photos of NGC7331, the core of the galaxy appears to be slightly off-center, with one side of the disk appearing to extend further away from the core than the opposite side.

The list below exhibits the number of subframes used with the exposure time for each filter. All the subframes were calibrated with Flats, Darks and Biases by PixInsight. Afterwards the subframes were combined and processed to the final image.

^* 2×2 binned

Total time for collecting data for this image is 12 hours.