Hickson 44 or the Leo Quartet from my ODK rig.
This is 5 hours Bin 1 Luminance plus 2 hours each Red and Green, and 3 3/4 hours Blue in Bin 2 and G2v calibration for a total of 12 3/4 hours. Not nearly enough.
Stacked in AstroArt 8, Sigma+Add with full calibration then each stack cropped and reduced gradient.
Luminance given a hard DDP with High Pass filtering to bring out differences in brightness, then a Richardson-Lucy deconvolution.
RGB stacks upscaled to match the luminance then given a soft DDP with no High Pass. Then a light denoise.
The individual RGB plates were co-registered with the the Luminance before being combined into a RGB plate. This was given a modest Saturation Boost and a slight Hue adjustment before LRGB synthesis. There were also several crops to remove alignment edges.
This is the whole image, a cropped and rotated version is in the Galaxy Cluster competition. Yep, there are some dodgy star cores (From the High Pass DDP). Nope, I can't be asked to "fix" them.