M81 is a large and brilliant spiral galaxy in Ursa Major constellation, with an estimated distance from the Milky Way of 12 million light years.
It has apparent dimension of 26.9’x14.1’ corresponding to a real diameter of 92000 light years, so it is a bit smaller than Milky Way.
M81 is the largest galaxy of a group containing 34 members, among which there is also the Cygar Galaxy M82.
On the bottom of the image it is visible also the faint dwarf galaxy Holmberg X, which is probably located behind M81 and was formed via the condensation of a tidal tail; its blue color is due to young massive stars formed only about 100 million years ago.
On the bottom left side of the image it is barely visible on the dark sky a sort of nebula: it is the IFN, Integrated Flux Nebula, a system of faint, mostly unlit, hazy filaments belonging to the high galactic latitudes of the Milky Way.
Optic GSO RC12 Truss - Aperture 304mm, focal lenght 2432mm, f/8
Mount 10Micron GM2000 HPSII
Camera Moravian G3-16200 with external filter wheel 7 positions
Filters Astrodon Gen2 E-Serie Tru-Balance 50mm unmounted LRGB
Guiding system OAG Moravian M68 with guide camera Moravian G1-0301
Exposure details L 41x300" bin2 -25
R 21x300" bin2 -25C
G 21x300" bin2 -25C
B 21x300" bin2 -25C
Total integration 8h40'
Acquisition Voyager, PHD2
Processing Pixinsight 1.8, Photoshop CS5, StarXTerminator, Topaz DenoiseAI
Location Promiod (Aosta Valley, Italy), own remote observatory
Date 5/6/7 November, 30 December 2021