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.
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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