The Nebulas of the Unicorn
This is a portrait of the main glowing nebulas amid star clusters in Monoceros, the Unicorn.
The main nebula at bottom is the Rosette Nebula, aka NGC 2237-9/45 surrounding the star cluster NGC 2244. But in this long exposure streams of nebulas extend north to connect to a large region of diffuse nebulosity around the Christmas Tree Cluster, NGC 2264, with the main nebula at top catalogued as Sharpless 2-273 and containing a region of bright blue reflection nebulosity. Just below that blue nebula is the dark, conical Cone Nebula. Just below it is the tiny (on this scale) Hubble's Variable Nebula, NGC 2261, a small bright triangular patch. The blue reflection nebula at upper right is IC 2169, surrounded by other smaller patches of reflection nebulosity including NGC 2245 and IC 446. The V-shaped dark nebula at top is LDN 1603. The star cluster just below that is Trumpler 5.
This is a stack of 8 x 12-minute exposures at ISO 3200 through an Optolong L-Enhance narrow-band nebula filter, blended with a stack of 8 x 8-minute exposures without a filter (for more natural star colors and the blue reflection nebulas) at ISO 800. All were with the Canon EOS Ra camera through the f/5 51mm William Optics RedCat astrograph with a Starizona filter drawer. Autoguiding was with the Lacerta MGEN3 autoguider which applied a dithering shift between each frame to help cancel out thermal noise when stacking. No darks or LENR were used here on this mild winter night at -5° C or so.
All stacking, alignment and blending was in Adobe Photoshop 2021. Luminosity masks (DM2, D and M) applied with Lumenzia helped bring out the faint nebulosity.