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Cave Nebula - Sh2-155 - SHO

Technical card

Resolution: 3333x2480

Dates: May 21, 2018May 27, 2018May 28, 2018June 2, 2018June 4, 2018June 5, 2018

Baader Ha 1.25" 7nm: 44x600" -20C bin 1x1
Baader Planetarium O3 1.25" 8.5nm: 31x600" -20C bin 1x1
Baader Planetarium SII 1.25" 8nm: 17x600" -20C bin 1x1

Integration: 15.3 hours

Darks: ~20

Flats: ~27

Bias: ~100

Avg. Moon age: 15.43 days

Avg. Moon phase: 76.15% job: 2094001

RA center: 344.051 degrees

DEC center: 62.583 degrees

Pixel scale: 1.215 arcsec/pixel

Orientation: 358.905 degrees

Field radius: 0.701 degrees

Locations: Nürnberg, Nürnberg, Bayern, Germany

Data source: Backyard


Object description (
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.



Thomas Richter


Sky plot

Sky plot


Cave Nebula - Sh2-155 - SHO, 


            Thomas Richter