Cave Nebula (Sh2-155) in the constellation Cepheus (Gábor Galambos)

Cave Nebula (Sh2-155) in the constellation Cepheus

The Cave Nebula (it was also named as Caldwell 9, Sharpless 155 and LBN 529) is a diffuse nebula within a larger nebula complex what consists of emission, reflection and dark nebulosity in the constellation Cepheus. The Sh2-155 is an ionized H II region with ongoing star formation activity. Its estimated distance from Earth is 2,400 light-years.
The name “Cave Nebula” – it’s widely known - was coined by a British amateur astronomer Patrick Moore who was the creator of Caldwell catalogue. Presumably, he determined from astrophotos that the structure and curve of the emission nebula resembles the mouth of a cave. Earlier this name was used to define Ced 201 (vdB 152) reflection nebula in the constellation Cepheus.
The Sh2-155 was first noted as a galactic emission nebula in 1959 in the extended second edition of the Shapless catalogue. This nebulosity is relatively faint to amateur observation. Its brightness is 7.7 magnitude. Some of the Cave Nebula's structure may be seen visually through a larger telescope under dark sky. Its details and its colours can be seen only on astrophotos.

Circumstances of taking this picture:
I took this picture over three nights in August and September, 2023. Two nights under dark sky (Bortle 3) and one night under Bortle 5 sky. 50% of the narrowband images were taken under dark sky and the other 50% under light polluted sky. I took the RGB images under dark sky for the real colours of the stars later (9th November, 2023).

Final
Original
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Title: Cave Nebula (Sh2-155)

Description: In this processing, I tried to bring out more details and make the image a little more alive.

Uploaded: ...

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Title: Astronomy Picture of the Day

Uploaded: ...

Dark Nebula
Fast Newtonians
Deep Sky Northern Hemisphere
vdB Reflection Nebula
IDAS NBZ Dual Band Nebula Boost Filter
Gothard Group (Magyarok/Hungarians)
ZWO ASI 294MC PRO
ZWO ASIAIR PRO USERS
The OSC Club (One Shot Camera)

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Status	Advanced success
Started	...
Astrometry.net job	8982144
PixInsight job	KKG74F9BE9IFKSXT2ZBZG2BEZ915274W
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	22h56m41s.50
RA (top/left)	22h56m41s.63
RA (top/right)	23h02m40s.70
RA (bottom/right)	22h56m41s.56
RA (bottom/left)	22h50m48s.99

Dec (center)	+62°31′57″.0
Dec (top/left)	+61°48′21″.8
Dec (top/right)	+62°46′16″.5
Dec (bottom/right)	+63°15′36″.6
Dec (bottom/left)	+62°16′44″.6

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