|Observation data: J2000.0 epoch|
|Right ascension||22h 57m 17.14s|
|Declination||+62° 28′ 33.4"|
|Apparent magnitude (V)||7.7|
|Apparent dimensions (V)||50.0'x30.0'|
|Absolute magnitude (V)||16|
|Designations||Sh2-155, Caldwell 9|
S 155, also known as the Cave Nebula, Sh2-155 or Caldwell 9, is a dim and very diffuse bright nebula within a larger nebula complex containing emission, reflection, and dark nebulosity. It is located in the constellation Cepheus.
Visually it is a difficult object, but with adequate exposure, makes a striking image. The nebula gets its name Cave Nebula from the dark lane at the eastern side abutting the brightest curve of emission nebulosity which gives the appearance of a deep cave when seen through a telescope visually.
Patrick Moore (1990). The Amateur Astronomer (11th ed), W.W. Norton & Company, ISBN 0-393-02864-X
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