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Sh2-155 Cave Nebula in BiColor Ha & OIII, 


            Douglas J Struble
Sh2-155 Cave Nebula in BiColor Ha & OIII

Sh2-155 Cave Nebula in BiColor Ha & OIII

Technical card

Resolution: 6000x4802

Dates:Aug. 13, 2017Aug. 17, 2017July 10, 2018July 12, 2018

Astrodon Ha 5nm: 96x240" (gain: 139.00) -20C bin 1x1
Astrodon Ha 5nm: 111x120" (gain: 201.00) -20C bin 1x1
Astrodon OIII 3nm: 142x240" (gain: 139.00) -20C bin 1x1
Astrodon OIII 3nm: 325x120" (gain: 201.00) -20C bin 1x1

Integration: 30.4 hours

Darks: ~50

Flats: ~50

Flat darks: ~50

Bias: ~250

Avg. Moon age: 25.15 days

Avg. Moon phase: 25.25%

Bortle Dark-Sky Scale: 6.00 job: 2153664

RA center: 344.431 degrees

DEC center: 62.627 degrees

Pixel scale: 0.371 arcsec/pixel

Orientation: 21.179 degrees

Field radius: 0.396 degrees

Locations: Backyard Red Zone Observatory, Taylor, MI, Michigan, United States

Data source: Backyard


I am adding on to 20 hours of integration time from last year. I was very disappointed from last year's 20 hours of integration time in the Hubble Palette with Ha, OIII and SII. I am still working on capturing SII data, but in the meantime I wanted to work on a more natural bicolor Ha and OIII palette with what I have captured this year and last year in Ha and OIII.

Sh2-155 (also designated Sharpless 155 or S155) is a diffuse nebula in the constellation Cepheus, within a larger nebula complex containing emission, reflection, and dark nebulosity. It is widely known as the Cave Nebula, though that name was applied earlier to Ced 201, a different nebula in Cepheus. Sh2-155 is an ionized H II region with ongoing star formation activity, at an estimated distance of 725 parsecs (2400 light-years) from Earth.

Sh2-155 was first noted as a galactic emission nebula in 1959 in the extended second edition of the Sharpless catalogue, being a part of the much larger Cep OB3 Association. Although Sh2-155 is relatively faint for amateur observation, some of its structure may be seen visually through a moderately sized telescope under dark skies.

Sh2-155 lies at the edge of the Cepheus B cloud (part of the Cepheus molecular cloud), and is ionized by young stars from the Cep OB3 association. It has been suggested that radiation from the hot O-type star HD 217086 is compressing the region, triggering the formation of a new generation of stars. A study of the region's young stellar objects by the Chandra X-ray Observatory and Spitzer Space Telescope shows a progression of stellar ages in front of the cloud, supporting the hypothesis of triggered star-formation.



Douglas J Struble
License: None (All rights reserved)

Sky plot

Sky plot


Sh2-155 Cave Nebula in BiColor Ha & OIII, 


            Douglas J Struble