A tiny nebula and the Milky Way's twin

On July 25 I took the opportunity to take advantage of some relatively clear skies (for a change) and point my scope to NGC 7331. The reason I picked this galaxy at this time is because a supernova was recently discovered very close to the nucleus of the galaxy (and because I wanted to compare my recent image of NGC 7331 with one I took back in 2017).

NGC 7331

Here is my latest image of NGC 7331.

NGC 7331 - July 25, 2025
EdgeHD11/ASI2600mm - LRGB - 3h 36m integration time

NGC 7331, often dubbed the “Milky Way’s twin,” is a striking unbarred spiral galaxy located about 40 million light-years away in the constellation Pegasus. With its elegant, moderately wound spiral arms and bright central bulge, this galaxy spans roughly 120,000 light-years, making it slightly larger than our own Milky Way. Viewed at a steep angle of 77 degrees, NGC 7331 presents a dramatic, elongated profile that reveals intricate dust lanes and a subtle asymmetry in its disk. Its core rotates in the opposite direction to the surrounding disk—a rare and intriguing feature. It is the brightest member of the Deer Lick Group.

The Deer Lick Group is an apparent galaxy grouping centered on NGC 7331. Surrounding it are several smaller galaxies—NGC 7335, NGC 7336, NGC 7337, and NGC 7340—that appear nearby in the sky but are actually much farther away, lying between 294 and 365 million light-years distant. This visual proximity is a result of line-of-sight alignment rather than gravitational association, rendering the “Deer Lick Group” a false group. Despite lacking physical interaction, the composition offers valuable insight into galactic structure, morphology, and scale.

Although a bit difficult to see the supernova, SN 2025rbs, is just to the right of the galaxy's central core. The image below, enhanced with high dynamic range (HDR) processing and cropped to show just the central core, shows the bright blue supernova glowing about as bright as the whole nucleus of the galaxy. 

SN 2025rbs was discovered on 14 July 2025 and it is a type Ia supernova. A supernova is a massive explosion that occurs when a star reaches the end of its life and can no longer hold itself together. In just a few moments, it releases an enormous amount of energy, briefly shining brighter than entire galaxies.

NGC 6210 - Turtle Nebula

NGC 6210, also known as the Turtle Nebula, is a striking planetary nebula located about 6,600 light-years away in the constellation Hercules. This cosmic sculpture marks the final breath of a sun-like star, which shed its outer layers to form a glowing shell of gas and dust. The nebula’s inner region resembles a delicate bluish “nautilus shell,” pierced by symmetrical jets of material streaming outward, while its fainter outer structure evokes the shape of a tortoise shell.

I'm not sure I see all the resemblance to a turtle but so be it.

NGC 6210 - The Turtle Nebula - July 4, 2025
EdgeHD11/ASI2600mm
LRGB - 1h 50m integration time

Although there is probably some significant Ha and Oiii signal in the object I chose not to capture that NB data since the broadband signal was so strong and I didn't want to spend the imaging time on this object.

A couple of more images from Mikey's Place

NGC 5906 - the Splinter Galaxy

NGC 5906, commonly known as the Splinter Galaxy, is a striking edge-on spiral galaxy residing approximately 50 million light-years from Earth in the Draco constellation. Its slender profile results from our vantage point, which aligns almost perfectly with the galaxy's disk plane—offering minimal view of its spiral arms but a spectacular showcase of its dust lanes and stellar population gradients. The central bulge appears subdued due to the edge-on perspective, while extended regions of neutral hydrogen and active star formation highlight dynamic processes within its disk.

I was able to capture this in a single evening due to its circumpolar location in the sky; away from my southern light pollution and providing basically the whole night of time available for imaging. As been the case here in Maryland there are very few clear nights and so I wanted to take advantage of this one. The only issues were the quality of the blue subs, which suffered a bit from low altitude and some thin clouds, and some image artifact in the bottom left corner. I specifically de-centered the galaxy as I was imaging it and cropped the final image to eliminate the artifact from showing in the final cut. I'm starting to think that these artifacts (I've had this happen before) may be due to reflections off the OAG pick-off prism due to a close bright star. Need to investigate this further. Revision B is the full frame view showing the artifact.

NGC 5906 - The Splinter Galaxy
June 25, 2025 - EdgeHD11 w/ASI2600mm Camera
5 hours integration time - LRGB

Abell 39

Abell 39 is a nearly spherical planetary nebula located roughly 7,000 light-years from Earth in the constellation Hercules. Spanning about five light-years in diameter, it showcases remarkable geometric symmetry—suggesting minimal interaction with the interstellar medium. The nebula’s faint, predominantly bluish glow arises from doubly ionized oxygen ([O III] emission), while its central progenitor star, once similar to our Sun, has shed its outer layers during the asymptotic giant branch phase.

Taken over a number of days in both 2024 and 2025 I ran into issues with smoke in the Maryland skies and a bit of an unplanned change of exposure durations in the RGB subs (2024 they were 120sec; 2025 60sec - my planning spreadsheet had marked the wrong sub-exposure times!).

Would love to add more data to this object but considering the number of nights I get to image I am on to other opportunities and I'm not even sure the added time would make a difference.

Abell 39
Sept 8, 2024 and July 4, 2025
EdgeHD11 w/ASI2600mm Camera
RGB (4hr 27min) & Oiii (5 hrs)