Sh2-155 (also designated
Caldwell 9,
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.
Captured during two nights in Oct. when travelling to a Bortle 4 area in rural Beijing.
3 FSQ85EDX used at the same time:
2 QHY600C and 1 QHY600M for Ha channel.
RGB image: 285 frames, each 300s
Ha image: 81 frames, each 300s
Total Stacking time:
RGB: 23 hours 45 mins
Ha: 6 hours 45 mins
HaRGB: 30 hours 30 mins
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