Sh2-261: Lower's Nebula (Alex Woronow)

Celestial hemisphere: Northern · Constellation: Orion (Ori) · Contains: LBN 862 · LBN 863 · LBN 864 · LDN 1587 · PGC 3097154 · Sh2-261

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Sh2-261: Lower's Nebula

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Sh2-261: Lower's Nebula

Sh2-261: Lower's Nebula

OTA: AG10 f/6.5
Camera: FLI Proline 6303
Observatory: Insight Observatory

Exposures:
H: 32 x 900 sec
O: 21 x 900
S: 46 x 900
Total Exposure time used: 24.75 hours
Image Width: 50 arcminutes

Processing: PixInsight, Topaz Studio2, Luminar Neo, custom scripts for image weighting and star replacement

This nebula was discovered by Mr. Lower and his son, Charles, in 1939. It is a rather faint emission nebula (surface brightness of about 10th magnitude) and is out-shown by the other stunning nebulae in the same constellation, Orion.

Although it looks like a planetary nebula, it is a simple emission nebula with a bluish reflection nebula in the center. However, this image uses narrowband filters (Ha, OIII, SII) mapped into their approximate true colors. The source of the blue in the center, recorded in the OIII narrowband images, is probably not OIII-caused. Instead, it is probably continuum radiation in the blue part of the spectrum caused by the reflection nebula. (If I had some RGB, I could separate the continuum from the emission lines and see if this hypothesis has merit.)

The star HD 41997, the blue star just below the image center, partially wrapped in the blue cloud, provides the intense radiation and winds that ionize the outer cloud and lights the reflection nebula.

Notice the asymmetry in the ruggedness of the emission nebula: smoother above and more structured below. Any speculations on why that is so? Differences in the initial structure or density of the cloud? A perspective difference? Perhaps we observe the leading edge at the bottom and trailing edge or the top? Or…?

Alex Woronow

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Status	Advanced success
Started	...
Astrometry.net job	8437495
PixInsight job	BAVP6SW1O6GALMWGHNPHSXQR8GTZDMLS
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	06h08m56s.876
RA (top/left)	06h10m40s.435
RA (top/right)	06h07m13s.685
RA (bottom/right)	06h07m13s.640
RA (bottom/left)	06h10m39s.781

Dec (center)	+15°46′38″.28
Dec (top/left)	+16°04′57″.74
Dec (top/right)	+16°05′04″.50
Dec (bottom/right)	+15°28′16″.53
Dec (bottom/left)	+15°28′10″.90

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Sh2-261: Lower's Nebula

Sh2-261: Lower's Nebula

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