Sh2-261 - Lower's Nebula (2023)

This colorful object image is a portion of Lower's Nebula or SH2-261. The nebula is a hydrogen alpha (Ha) region about 3,200 light-years away in Orion, specifically where the hand meets the club. It is named after amateur astronomer Harold Lower and his son Charles who discovered this nebula in 1939 in their home of San Diego. The nebula is located on the outermost edge of the Milky way galaxy, on the border of the galactic region between the Orion and Perseus arm.

There was no pre-planning on this object as I quickly was looking for something available to image in my FOV with the Edge800 in preparation for galaxy season. The weather has not been kind lately and for whatever reason the data had heavy gradients possibly due to weather, imaging with the moon, old flats, or all three. I did not make a fresh set of flats and using the ZWO ASI294 MC with dual band filters which isolate hydrogen is problematic anyway - the SONY IMX294CJK has some type of film on it that shows up when using Ha filters. It is usually subtracted out by the flats but the flats have to be really good.

Since I did not get the whole nebula because it is very large anyway, I cropped it around one of my favorite parts, the lower portion, and got rid of some of the gradients in the process. The lower portion where the gas seems to be concentrated most and it has the sharpest detail. I was happy the stars came out OK especially since SCTs are more fussy than refractors (some people would find these stars unacceptable). Of course when I actually get around to imaging galaxies a new set of flats will be made.

Sh2-261 - Lower's Nebula (2023)
Dates: 2-15-23, 2-18, 2-24, 2-26, 3-8
Camera: ZWO ASI294MC-Pro
Telescope: Celestron EdgeHD 800
Barlow: None
Focal Length: 2032mm (native), 1400mm
F/10 (native), F/7
Focal Reducer: Celestron 0.7 Reducer Lens
Mount: Orion Atlas Pro
Filter Adaptor: ZWO Filter Drawer
Filter: IDAS NBZ
Focuser: ZWO EAF
Autoguiding: ASI120 Mini attached to an Orion ST80
Exposure: IDAS NBZ 273 x 180
Gain: 139
Offset 0
Temp: -10 C
Processing: Asiair app, PixInsight, Photoshop, StarXTerminator, BlurXT, NoiseXT, GHS, Bill's Star Reduction, Bill's Color Masks.

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