"M108, or the Surfboard galaxy, is located in the constellation Ursa Major approximately 46 million light-years away. M108 was discovered by Pierre Méchain in 1781 three days after he discovered M97. Charles Messier’s notes state that he observed the galaxy in 1781 but never took an accurate position of it or officially added it to his catalog. M108 was finally added to Messier’s catalog in 1953 by astronomer Owen Gingerich. At the center of M108 is a supermassive black hole estimated to be 24 million times as massive as the Sun. "https://www.nasa.gov/feature/goddard/2018/messier-108
"The Owl Nebula Messier 97 (M97, NGC 3587) is one of the fainter objects in Messier's catalog. It is one of the four planetary nebulae in that catalog, and situated in constellation Ursa Major. M97 was discovered by Pierre Méchain on February 16, 1781
M97 is one of the more complex planetary nebulae. Its appearance has been interpreted as that of a cylindrical torus shell (or globe without poles), viewed oblique, so that the projected matter-poor ends of the cylinder correspond to the owl's eyes. This shell is enveloped by a fainter nebula of lower ionization. The mass of the nebula has been estimated to amount 0.15 solar masses, while the 16 mag central star is believed to be of about 0.7 solar masses. Its dynamical age is about 6,000 years. (from Stephen J. Hynes, Planetary Nebulae)."  http://www.messier.seds.org/m/m097.html

This is the fourth Planetary Nebula we try to develop in several night sessions.  The files checked also used calibration.  The final stack used the better frames of each session in a second revision.

The first and second version was made in May 2020, then another in September 2020.  None of those versions convinced me at all.  I try to rework a stack done already and could bring more clarity in the nebula as in the galaxy but still I think can be done a better work, maybe re choosing better frames to stack (less is better...)

There is a session done by Mauri this year and soon or later I will try to incorporate and do another version of this magnificent pair of DSO.

Process May 2020, Sept. 2020 and final version Nov. 2021
https://twitter.com/AstroOtus/status/1311000551233118211