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 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. (from Wikipedia)
This image is 8 hours total exposure taken over three nights, November 18-19 and 22, 2014. There is 90 minutes of exposure through a hydrogen-alpha filter to bring out the red nebulosity. I imaged this object in the fall of 2010 but wasn’t happy with the weather or my processing. Click on the image above for a larger view.