I have revisited this galaxy in 2020 and took a image with long duration of 19 hours. (43 images of 20 minutes each for Luminance & 9 images each of each color of 10 minutes each).
One of the brightest galaxies in planet Earth’s sky is similar in size to our Milky Way Galaxy: big, beautiful M81. This view reveals M81’s bright yellow nucleus, blue spiral arms, and sweeping cosmic dust lanes with a scale comparable to the Milky Way. Scrutiny of variable stars in M81 has yielded one of the best determined distances for an external galaxy — 11.8 million light-years.