The Cave Nebula | Sh2-155

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The Cave Nebula

Sh2-155 • Emission nebula • Cepheus • 2400 light-years from Earth

🗓️
Nov & Dec 2021

The Cave Nebula Sh2-155 in Cepheus, imaged from a light-polluted city

Overview

The Cave Nebula, also known as Sh2-155, lies around 2400 light years from Earth in the constellation Cepheus. It’s a complex star forming region where intense radiation from nearby hot, young stars compresses surrounding gas and dust. This process triggers successive waves of star formation, carving dark cavities and bright emission fronts that give the nebula its distinctive appearance in long-exposure astrophotography.

Background

This was the most difficult image for me so far. I worked at the editing all day before I finally had something I was happy with — the 7th version! Part of the reason it was so tough is because of the high noise levels. I cut this project short at 18 hours because brighter winter targets are getting high in the sky, and I want to move onto them. Also, the integrated shot had banding issues, which I’ve never had before. I had a tricky time removing them until I discovered that PixInsight has a utility called CanonBandingReduction that fixed it in literally three seconds!

I normally crop my images in at least a little, but during editing it was obvious I’d captured a fair amount of surrounding nebulosity not often seen in images of the Cave Nebula. So, I kept it wide.

Framed astrophoto taken from a light-polluted city, available to buy as a fine art print

Explore the field

1.0×
Objects in this field 20 objects
Cave NebulaSh2-155
HII regionAlso catalogued as C 9 · LBN 529
ASCC 125
Open cluster
Sh2-154
HII regionAlso catalogued as LBN 521
UBC 178
Open cluster
Gulliver 19
Open cluster
FSR 0416
Open cluster
vdB 155
Reflection nebulaAlso catalogued as LBN 524 · DG 188
FSR 0406
Open cluster
LBN 522
HII region
NGC 7419
Open clusterAlso catalogued as Cr 453
FSR 0404
Open cluster
LDN 1218
Dark nebula
LDN 1216
Dark nebula
LDN 1215
Dark nebula
LDN 1224
Dark nebula
LBN 527
HII region
LDN 1212
Dark nebula
LDN 1210
Dark nebula
LDN 1211
Dark nebula
LDN 1220
Dark nebula
About the labels and credits

Positions and outlines are calculated from a plate solution of this photograph. Outlines are catalogue guides and may not follow every visible filament. Additional catalogue objects may be faint or indistinct in this exposure.

Plate solving and annotation data: SkySolver, by Dominik Sito. Stars: Gaia DR3 and Hipparcos (ESA). Deep-sky data: OpenNGC © Mattia Verga (CC BY-SA 4.0), SIMBAD and VizieR (CDS). Names: Wikipedia (CC BY-SA 4.0) and IAU WGSN. Catalogue overlay adaptations, including styling and selected display names, are shared under CC BY-SA 4.0. Photograph © Lee Pullen.

Imaging details

Total exposure
18 hours
Dates captured
November & December 2021
Location and sky
Bristol, UK (Bortle 8)

Equipment and software

Telescope
Askar FRA400
Camera
ZWO ASI 2600MC Pro
Mount
Orion Sirius EQ-G
Guiding
WO 32mm + ZWO ASI 120MM Mini
Control
ASIAIR Plus
Software
PixInsight, Lightroom
Image by
Lee Pullen

Exposure by filter

Optolong L-eXtreme

Channels
Hα / OIII
Subframes
540 × 2 minutes
Integration
18 hours
View subframe and stack

Single subframe and integrated stack, both with a simple stretch applied.

Single subframe
Single subframe2 minutes
Integrated stack
Integrated stack18 hours

Kit list

This is the equipment I used to capture the image.
Affiliate links help support the site at no extra cost to you.

Guidescope: William Optics 32mm Slide-Base Uniguide
Read my review
Buy from Astroshop.eu
Buy from High Point Scientific

Example astrophotography image promoting one-to-one online astrophotography masterclasses

Seestar S50 image

This photo of the Cave Nebula was taken using my Seestar S50 telescope.

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2 thoughts on “The Cave Nebula | Sh2-155”

  1. Craigar on CN says:

    Astounding! Your “slider” comparison makes it look like magic. With 120 second subs and fast f/5.6 you probably use no gain on the camera for benefit of maximum dynamic range?

    Reply
    1. Lee says:

      Thanks! I always use Gain 100 (set via the ASIAIR Plus).

      Reply

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