Hemisphere:  Northern  ·  Constellation: Cepheus (Cep)
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Cave Nebula (Sh2-155), 


Cave Nebula (Sh2-155)
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Cave Nebula (Sh2-155)

Technical card

Imaging telescopes or lenses: Sky-Watcher Espirit 100ED Super Apo

Imaging cameras: QSI 660 WS

Software: ImagesPlus 6.5 MLUnsold Digital Imaging  ·  GIMP  ·  Deep Sky Stacker  ·  Regim  ·  Software Bisque The SkyX Professional  ·  Imagenomic LLC Noiseware

Filters: Astrodon 31mm LRGB E Series Gen 2 1.25"

Accessory: orion starshoot autoguider

Dates:July 28, 2020Aug. 19, 2020Aug. 20, 2020

Orion Extra Narrowband Filter Ha 1.25": 33x600" -16C bin 1x1
Baader Planetarium LRGB 36mm: 33x300" -16C bin 1x1
Baader Planetarium LRGB 36mm: 40x600" -16C bin 1x1

Integration: 14.9 hours

Avg. Moon age: 3.48 days

Avg. Moon phase: 21.32%

Bortle Dark-Sky Scale: 4.00

Basic astrometry details

Astrometry.net job: 4242273

RA center: 22h 57' 34"

DEC center: +62° 30' 50"

Pixel scale: 0.844 arcsec/pixel

Orientation: 356.210 degrees

Field radius: 0.819 degrees

Resolution: 5470x4345

Locations: Back Yard - New York, Pittstown, NY, United States

Data source: Backyard


The Cave nebula (Sharpless 2-155) is an interesting region in the constellation Cepheus that exhibits both hydrogen-alpha emission and reflection nebulae. In order to capture both, a synthetic luminance was created that combines hydrogen-alpha with broadband luminance. Although I was not able to travel to a dark site to work on this image, some really good weather helped the quality of the data.

One of the interesting features in this image is the small, dark nebula at the left side of the image. It reminds me very much of the lowercase Greek letter Xi. Does anybody know if it has a name?

Edit 9/2/20: there was just a little bit of unwanted green tint lurking in the darker areas, which I found after turning all the lights off.... I hate it when that happens! The revision has been de-greened.



  • Cave Nebula (Sh2-155), 


  • Cave Nebula (Sh2-155), 


  • Final
    Cave Nebula (Sh2-155), 




Description: This revision has better noise reduction (Topaz AI), diminished halos around the stars, and a different method of combining Ha and luminance. I thought this was one of my best images when I first processed it, but after re-working it, the previous version looks like garbage! Now it just needs 20 more hours of integration this coming summer.

Uploaded: ...

Sky plot

Sky plot


Cave Nebula (Sh2-155),