Sh2 -261 , also sometimes known as the Lower Nebula , is a visible emission nebula in the constellation of Orion .
It is located in the northernmost part of the constellation, about 6° west of Alhena (γ Geminorum), and is easily visible in long exposure photos taken even with medium power amateur instruments. The nebula lies in the clear trail of the Milky Way in opposition to the galactic center and is surrounded by rich background star fields. The best period for its observation in the evening sky falls in the months between January and May, and although it is located in the northern celestial hemisphere, it can be observed from all populated areas of the Earth .
SH2-261 is an H II region located on the outermost edge of the Orion Arm , at the limit of the galactic region between it and the Arm of Perseus.  It is located on the line of sight of the southernmost part of the Gemini OB1 association. One of the stars responsible for the ionization of the region's gases would be the blue star HD 41997, a fugitive star of spectral class O7.5V.  To this are added other stars, including the blue star BD + 15° 1079, of class B0. This star has sometimes been referred to as being of class O7, thus shifting the distance of the nebula up to 2000  parsecs due to the increase in the discrepancy between absolute magnitude, evidently brighter in a class O star, and apparent magnitude.   Through the analysis of the other ionizing stars a distance of about 1000 parsecs (3260 light years ) was calculated, which seems to be more reliable, also given the re-determination of the star BD + 15° 1079 as belonging to class B0.   [Wikipedia Italian].

CAPTURE Information: This is a Two-Panel Mosaic.
The image was captured with the iOptron CEM120 mount, the venerable Meade 12"LX200 SCT, and my QHYCCD QHY294m Pro mono CMOS camera at F7.16 (2182mm FL).  Image subs were taken through Astronomik's narrowband filters of Ha, SII and OIII.

IMAGE information -- 2022
The following is a breakdown of each panel (i.e. panel 1 and panel 2 respectively).
Ha : 34 and 35 subs (2.833 and 2.92hr) on Feb 9th, 15th, 18th and 19th.
OIII : 30 and 24 subs (3.33 and 2.00hr) on Feb 9th, 15th, 18th and 19th.
SII : 24 and 24 subs (2.00 and 2.00hr) on Feb 9th, 15th and 18th.

All exposures were at 5 minutes (300s) each, 1600 gain, 56 offset, 1x1 bin and -10C.

Each two panels of Ha, SII and OIII were individually integrated, and then combined. The three assemblies then created the Hubble Palette, using PixelMath and the following “SHO” formula:
Red = SII
Grn = Ha
Blu = OIII

Luminance was created using only subs from the Ha filter.

Processing was done with PixInsight, following (for the most part) kayronjm's tutorial of Feb. 24th from several years back. Credit also goes to Rick Stevenson’s Color Mask Script and Christopher Gomez’s tutorial.

COMMENTS:
North is up (or not), and this is a slight crop.  This was my first effort with this target.  

There is quite a bit of small star smearing.  I was hoping for it to not be a problem with the amount of integration, but it was.  You’ll see it (mostly in the corners) if you look hard enough.

I continue to image with my new QHY294m Pro mono cmos camera, and have settled on the “gain” and “offset” (1600 and 56 respectively), and the use of Lights, Darks, Flats and Flat Darks for processing.