This is an LRGB image of NGC7331 and Stephan's Quintet. This is one of my favorite autumn galaxy regions, and I'm pleased how well it fits the FOV with the C11 + 0.7x Reducer + ML16200.

NGC7331 is an unbarred spiral in Pegasus at distance 40Mly, diameter of 120kly. Close to it are unbarred spirals NGC7335 and 7336, barred spiral 7337 and elliptical 7340, at distances 332, 365, 348 and 294 Mly, respectively.

Stephan's Quintet consists of five galaxies in visually close proximity, four of which in physically close proximity (Hickson Compact Group 92) that will eventually converge. The brightest is spiral NGC7320 at closer distance 40Mly. The other four at at 210-340Mly distance: NGC7317, 7318A, 7318B, 7319. The smaller galaxy to the upper left from the main group is likely associated, 7320C.

I had several technical problems with the acquisition and processing. The foremost issue was a vibration induced by the camera fan. I've faced this for quite some time assuming it was the fan itself, but I am now convinced that the load on the AP Mach1GTO mount is just large enough such that the vibration is induced. Thus far I have been unable to dampen this vibration.

The vibration elongates the stars mostly along the DEC axis, and enlarging this image will show the misshapen stars. Additionally, the brighter stars were saturated and likely distorted by the vibration, although in a different direction. This implies that I would benefit from the future choosing a shorter exposure than 300s when using the C11 + 0.7x Reducer. I attempted to reduce the star sizes through several processing steps including deconvolution and morphological transformation. This helped, however the elongation is still apparent.

Despite the vibration problem and elongated stars, I am moderately pleased with the result with the hopes of better results in the future once the vibration has been properly dampened. I pushed the color saturation further than I usually do, mostly just to make the image more interesting and compensate for the lousy stars. I have done an historically better job with a couple of sharpening steps that produce a pleasing result at least when the image is viewed in its entirety. Zooming in closer will reveal all kinds of problems, most of which originate with that blasted vibration.

I'd like to publicly thank John Hayes for advising me on the vibration issue. We first thought it might be an optics issue with the C11 or imaging train, but by running some tests we eventually discovered the incessant fan vibration coupling with the heavy load. It was a helpful interaction for me nonetheless as I picked up some clever optics diagnostic tips from John.