There is a nebula of the heart, of the skull, of the fetus, of the ear, of the eye (several), of the retina, of the hands, of the skeleton... but there is no nebula of the brain. In 2020 Chuck Ayoub (Chuck'k Lower Nebula) shared his photograph of Sh2-261 (Lower Nebula) on Astrobin, and titled it “Big Brain Nebula”. As a neurologist I am going to accept his proposal. In addition to its outline and a brain stem, I would add the beginning of the spinal cord, a protruding cerebellum, a blue central thalamus, and gyri in the cortex. It is true that at many points there is a flight of ideas, but that is typical of a cosmic brain.  I have put the name in quotes because it is a personal title for the object, not a common name, much less a recognized one. I've sometimes been confused by photo titles, thinking they were accepted names.

Sh2-261 was discovered in 1939 by Harold and Charles Lower, father and son, amateur astrophotographers and telescope builders from California. It is an emission nebula, although it is incorrectly classified as a supernova remnant in the Sharpless catalogue. It is ionised by the star HD41997, magnitude 9.47, the brightest in the bluish reflection region.  It contains the bright nebulae LBN 862 and 864, several dark nebulae (Dobashi 4665, TGU H1364 P13, TGU H1364 P14), and an open cluster ([KPS2012] MWSC 0725). It is an HII región, located at the outermost edge of the Orion arm of the Milky Way. In its center there is a curious bean-shaped reflection cloud, at the base of which (to the south) is the star HD41997.

The image is a SHO composition taken with QHY 268C color camera. The stars were taken with a Baader Neodynium anti-pollution filter, also capturing a weak RGB nebulosity that I did not use for the nebula. The narrow band was obtained with an Optolong L-Ultimate filter (HII/OIII, 3 nm, 2”) and an Askar Color Magic D2 filter (OIII/SII, 6 nm, 2”). The red channels of both were for the HII and SII masters, while the OIII channel was the weighted sum of the G and B channels obtained with both filters. The masters of the three filters were processed until they were stretched, then the reconstruction of the SHO channels and the composition with the Hubble palette were carried out.

It is a large object (more than one degree  in diameter), and although its surface brightness is low, I have not found it more difficult to photograph than other more popular objects. If I were to process my data again I would use NoiseXT more cautiously. I think its action has been excessive in high light areas compared to the background. In my OIII the definition of the central región was somewhat better. Perhaps I will try its use with masks in the future.  Russell Croman's tools are very powerful and apparently simple, "for dummies" compared to the classic ones. However, perhaps due to their power they require greater learning, both technical and aesthetic. We also cannot forget the classic tools. Hue correction on this photo was strong, and produced chrominance noise that was excellently corrected with TGV.