SH2-261 Lower's Nebula in Orion

On the clear, cool (i.e. cold) evening of 30 December 2025 I pointed my ZenithStar 81 telescope at a target I had not observed before, namely Sharpless 2-261, also known as Lower's Nebula.

 

It is a faint emission nebula located in the constellation Orion. Sh2-261 is an ionised hydrogen region energised by the ultraviolet radiation of nearby hot stars. This nebula lies roughly 3,300 light-years from Earth and spans about 50 light-years in diameter. Observations in radio and infrared wavelengths have revealed dense pockets of gas and dust within the nebula, indicating ongoing star formation. The primary ionising source is believed to be a massive, hot star whose intense ultraviolet radiation excites the surrounding hydrogen gas, causing it to emit the characteristic red glow.

 

The nebula is called "Lower's Nebula" in honour of Harold Lower, an American amateur astronomer and astrophotographer, who first photographed it in 1939 using a homemade 6-inch telescope. His discovery was notable because, at the time, most deep-sky objects were catalogued by professional observatories. Yet Lower managed to capture this faint nebula from his backyard, much like I did, but I had the advantage of finding it in my star catalogue.

 

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Telescope: William Optics ZenithStar 81 APO

Mount: SkyWatcher EQ6-R Pro

 

Controller: ZWO ASIAIR Plus 256G

Main Camera: ZWO ASI533MC Pro at -10C

Filter:Optolong L-eNhance filter

Focuser: ZWO EAF

Guide Camera: ZWO ASI290MM Mini guidecam

Guide via: William Optics Refractor 50/200 mm

 

Stacked from:

Lights: 52 at 180 seconds, gain 101, temp -10C

Darks: 30 at 180 seconds, gain 101, temp -10C

Flats: 30 at 8.9 seconds, gain 101, temp -10C

Dark Flats: 30 at 8.9 seconds, gain 101, temp -10C

 

Bortle 4 sky.

 

SW Tools:

Stacked in AstroPixelProcessor

Processed in PixInsight, stretched using Multiscale Adaptive Stretch,

Photoshop CS4 for labels.

 

 

Done