This image shows a group of (interacting?) galaxies in Triangulum that is seldom imaged.  The galaxies have low surface brightness and appear to be obscured by dust from the Milky Way, lending a dull reddish tint.  The arrangement of the galaxies reminds me a bit of Markarian’s Chain, but on a much smaller and fainter scale.

This image is Part 1 of my “Triangulum Project” with the Esprit 100ED refractor.  The idea here is to rack up a lot of integration time on a fairly wide field of view that contains several interesting galaxy groups in order to get several finished images out of one project.  By having a large number of subs and applying 2x drizzle during stacking, the final image scale is 0.7” per pixel, making it look like the image was taken with a larger telescope.  I have had a lot of success with this approach during 2022.  This particular image has about 21 hours of integration, but it will yield at least four finished images, so 5 hours per finished image is not so bad.  Data collection was done on eight nights between August 25 and Nov 22, 2022 from my Bortle 4+ backyard in upstate NY.

The showpiece of this image is NGC 974 (UGC 2049), the propeller-shaped galaxy with the distorted arms.  It certainly looks to me like it is being torn apart by its neighbors.  TheSkyX lists its apparent size as only 1.7’x1.2’, but those dimensions correspond to the bright nucleus.  My image suggests that it spans more like 4.6’x3.5’ including the faintest extremities of its spiral arms.  The surface brightness of the arms is really quite low, requiring a lot of integration time and a brutal stretch of the luminance channel.  NGC 974 is classified as type SAB(rs)b, and it apparently has a weak bar.

NGC 969 (UGC 2039) is the bright galaxy to the upper left of NGC 974, which is listed as a Type S0 lenticular galaxy.  It sure looks like a barred spiral in my image, and other imagers have made the same remark.  It appears to be 2.6’x2.3’ or so in my image, and it is listed as having a visual magnitude of 12.3 in TheSkyX, a little brighter than NGC 974 at mag. 12.8.

The small “double galaxy” to the left is NGC 970.  These two elliptical galaxies may be interacting, or one of them may be in front of the other.  Nearby NGC 971 is thought to be a star, but it seems like a catalogue error to me.

The bright galaxy pair near the right edge of the image consists of NGC 978A and 978B (UGC 2057).  Each of these elliptical galaxies is classified as type S0.  It is not clear whether they are interacting or not.

In the upper left corner of the image are two interesting galaxies.  The leftmost galaxy is 2MASX J02332722+3306171, a barred spiral with an outer ring.  I was not able to find its morphological type in SIMBAD, so your guess is as good as mine. 

To the right is the peculiar looking galaxy 2MASX J02333881+3300557 that appears to have a double nucleus.  It is not clear if there are two merging galaxies here, or if one or both of the “nuclei” are actually orange stars in front of a single galaxy.  My 4” refractor is not going to tell you the answer.  However, there appears to be a faint spray of stars extending upward toward the edge of the image that is almost lost in the noise, which does suggest that something unusual is going on here.  Does anyone have a 1.8 meter astrograph I can borrow for a night?

Here are a few words on processing.  The luminance stack had 282 subs that were a mixture of long (300 s) and short (75 s) exposures.  The original idea was to use the short exposures to tone down the brighter stars, but it did not work out, so I just threw all the luminance subs into the food processor (I mean Deep Sky Stacker) together and pressed “blend.”  Even so, the stretching required to show some of the fainter features was so extreme that I needed to spend extra time on star cosmetics and noise reduction.  Stars were removed using Startnet++ and shrunken to reduce halos. The starless image was smoothed using a blend of standard noise reduction (Noiseware) and Topaz AI.  I hesitate to use Topaz AI on my images, but with the AI sharpening features completely turned off and stars removed, it really can help tame the noise in the dark sky background.  Blending the resulting over-smoothed, starless image with standard noise reduction then produces acceptable noise levels in the sky background without ruining the image.


Acquisition details:  Aug 28, Aug 28, Sept 2, Sept 24, Oct 27, Oct 30, Nov 19, and Nov 22, 2022

Total integration time: 20.8125 hours (74,925 s)

Luminance: 11 hours 48.75 min. total;  187x75s (Mode 1, Gain 56, Offset 10) and 95x300s (Mode 3, Gain 14, Offset 10).=

RGB: 9 hours 0 min. total; 52x150s (Mode 1, Gain 56, Offset 10) and 41x600s (Mode 3, Gain 14, Offset 10)


References

1) Rick Johnson, “NGC0974.”  Mantrap Skies Catalog.  https://images.mantrapskies.com/catalog/NGC/NGC0974-NGC0969-NGC0970-NGC0971-NGC0978/index.htm

2) University of Strasbourg, SIMBAD database.  https://simbad.u-strasbg.fr/simbad/sim-fid

3) Software Bisque, TheSkyX databases.