St. Catherine’s Wheel (Messier 99) is a grand design galaxy located in the constellation Coma Berenices. Situated roughly 50–60 million light-years from Earth, the galaxy spans about 85,000 light-years in diameter, making it slightly smaller than the Milky Way.

This image was captured using a Nikon Z7 II and a Nikon Z 600mm f/6.3 lens. The final image is a stack of 125 exposures of 40s each at ISO 3200, for a total integrated exposure time of 83 minutes.  Star tracking was performed using a Fornax LighTrack II.

Individual frames were registered in DeepSkyStacker and subsequently sigma-clip averaged using program astro-sca. Sigma clipped averaging helped eliminate meteor streaks present in numerous frames. The resulting stacked sigma-clipped averaged file was then processed using program astro-color-stretch. Stretching was a two pass asinh stretch followed by a single S-curve adjustment, and color correction. The image was sharpened with a 40 iteration of Richardson–Lucy deconvolution, followed by four-level Discrete Meyer wavelet enhancement. All of these processing operations were performed using astro-color-stretch.

Some final refinements were done using Capture One, followed by some additional noise reduction and sharpening using Topaz DeNoise AI.