①About the Target:
Bode's Galaxy, also known as Messier 81 (M81), is a grand design spiral galaxy located in the constellation Ursa Major. M81 is one of the brightest galaxies seen from Earth. It has a near-perfect spiral shape, with prominent, well-defined spiral arms winding from the central region outwards.
The galaxy is located approximately 11.8 million light years from Earth and has an apparent magnitude of 6.94. Its designation in the New General Catalogue is NGC 3031.
The galaxy’s size, brightness and proximity make it a popular object among both amateur and professional astronomers, as it is easy to observe even in smaller telescopes. M81’s active galactic nucleus contains a supermassive black hole with about 70 million solar masses, or 15 times the mass of the black hole in the Milky Way Galaxy, and has been an object of extensive study. The angular size of M81 roughly corresponds to that of the full Moon.
②Integration Info
The image consists of the following data taken by me only:
Lum 300x 300s = 25h
Red 60 x 300s = 5h
Green 60 x 300s = 5h
Blue 60 x 300s = 5h
Ha 108x 600s= 18h
Overall: 588 frames, 58 hrs.
Date: 2024, Jan 5,6,13,15,19,20,21,23,29 / Feb 3, 6 to 17.
Location of Remote Observatory: Daocheng Obs, Sichuan,China
Raw data capture and process: John Chuhong Yu
③Note
I went through many pics capturing M81 and most of them did emphasize IFN around it ,especially for pic captured with short focal length.
From my previous attempt on M74, I know 25 hrs on Lum @ F6.4 is hardly good enough. But I still tried my best to stretch them out while keeping balance with the galaxy which is way brighter.
I plan to take a 2X1 mosaic to present M81 and M82, and it is planned to be done at the end of March, with over 100 hrs exposure in sum.
④Core Ha
Similar to M31, M81 also has a whirlpool shape core rich in Ha info. I happened to notice it when processing my Ha data and tried to add blend them into my previous revision, yet failed and resulted in the overexposure in the core region. The SNR of 18hrs of Ha is unsatisfying, but you can still find some detail. The subtracted Ha is shown in revision C.
BTW it really looks like Rasengan from Uzumaki Naruto ;)
Hope that you enjoy this image!
John Yu
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