NGC 973 and IC 1815 are the brightest members of this group of galaxies in Triangulum.  There is a thin layer of dust obscuring essentially the whole field of view, imparting a dull reddish tint to the galaxies and most of the stars.  There are just a few blue stars present, and I wonder if they are foreground objects that lie in front of the dust, or if they are just shining through a thinner layer of dust.

This image is Part 2 of my “Triangulum Project” with the Esprit 100ED refractor.  The idea here was 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.

NGC 973 is an edge-on spiral with a prominent dust lane.  According to SIMBAD, it is a type Sb spiral that measures 2.08’ x 0.46’.  It is reminiscent of the more frequently imaged galaxy NGC 891 in Andromeda, which is a much larger target at 11.7’ x 1.6’.  A galaxy so small seems like a poor target for a 100 mm refractor, but larger (ground-based) telescopes do not resolve much additional detail beyond what is shown here.  Comparing my “puny refractor” image to the one taken with the 1.8 m Pan-STARRS telescope, there is not much new to see. 

The bright galaxy below NGC 973 is IC 1815, a 14th magnitude barred spiral of type SB0 that measures 1.3’ x 1.2’.  It looks a bit like a blurry image of Saturn taken after the corrector plate on your SCT got covered by dew!  To its lower left are two edge-on galaxies, both of 17th magnitude:  PGC 213027 (designated as 2MFGC 2027 in SIMBAD) and PGC 213028 (also known as LEDA 213028).

To the upper left is PGC 213029 at 16th magnitude and 0.8’ x 0.3’ according to TheSkyX databases.  The little spiral galaxy to the upper right of the main group is PGC 9751, which has the oddball designation Z 505-7 in SIMBAD.  Although it measures only 0.48’ x 0.24’, there are some hints of spiral structure in this image. 

This image is just loaded with fainter galaxies.  To the left of the blue star, upper left corner of the image, are PGC 3640534, PGC 3088861, PGC 2006599, and PGC 86803, each ranging from 16th to 18th magnitude.  The 17th magnitude galaxy in the lower left corner is PGC 9844.  To its right near the bottom of the frame is 2MASX J02353152+3220376, which has a blue star right in front of it.

(The rest of this description is nearly the same as my previous image, but it is included here for completeness).

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, “NGC0973.”  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.