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Monday, January 24, 2011

Sh2-155, the "Cave Nebula", reprocessed

Since my processing technique gets better and weather doesn't give any support, I have reprocessed some older images. There is now star colors added and other processing is tweaked too.

Sh2-155, the "Cave Nebula" as a wide field image
Ra  22h 57m 17.14 Dec +62° 28′ 33.4"

Image is in HST-palette, (HST=Hubble Space Telescope)
from the emission of ionized elements, R=Sulfur, G=Hydrogen and B=Oxygen.
Star colors are mixed from the NB channels, Red=H-a, G=O-III and B= 85%O-III + 15%H-a.

The Cave Nebula, Sh2-155 or Caldwell 9 is a very diffuse nebula within a larger nebula complex containing emission, reflection, and dark nebulosity. It is located in the constellation Cepheus.
The reflection, wide band, component can't be seen in my image, since this is a narrowband one. 
Distance is about 2400 light years.

Natural color composition from the emission of ionized elements, R=80%Hydrogen+20%Sulfur, G=100%Oxygen and B=85%Oxygen+15%Hydrogen to compensate otherwise missing H-beta emission. This composition is very close to a visual spectrum.

Image is shot with a QHY8 and the Tokina AT 300mm f2.8 lens at full aperture.
Original versions from October 2008, with technical details:

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