Cat's Eye Nebula
This is one of the most challenging targets I've ever worked on and there is still a LOT of room for improvement. After the first two nights of 5-minute exposures I went another night with 10-minute exposures. What you see is 13 hours of total exposure and I had to suppress the core when stretching to maintain the details of the eye. This is NGC6543, the Cat's Eye Nebula.