The Cave Nebula
Sh2-155
The Cave Nebula (also designated Caldwell 9 or Sh2-155) is a diffuse nebula in the constellation Cepheus, within a larger nebula complex containing emission, reflection, and dark nebulosity. Sh2-155 is an ionized H II region with ongoing star formation activity at an estimated distance of 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.

Awarded Astronomical Picture of the Day (APOD) on Astronomia.com




Image Details
Date
August 28 & September 5 & 6, 2023
LOCATion
Hannover (Germany)
Sky Quality
Bortle 5
Telescope
Celestron RASA 8 (203/400 f/2)
Mount
Skywatcher EQ6-R Pro
Main Cameras
ZWO ASI 2600 MC Pro
Gain 100, Offset 18, -10°
TS 2600 MP
Gain 100, Offset 50, -10°
Focuser
Celestron Motorfocus
Processing
Astropixelprocessor, Photoshop, Pixinsight
Filter
Baader H-Alpha Highspeed 3.5nm
Baader O-III Highspeed 4nm
Baader UV/IR-Cut Filter
Exposure
RGB: 326 × 60″ (5h 26′)
Ha: 175 × 120″ (5h 50′)
OIII: 176 × 120″ (5h 52′)
Total: 17h 8′
Guiding
ZWO ASI 120MM, PHD2
Calibration
Flats, Darks, Darkflats
Software
N.I.N.A., EQMod
Other
Artesky Filter Holder
  
  
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