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Sunday, December 9, 2012

The Cave Nebula

I shot this target 29.11. but I'm publishing it now since this one was very hard to process due to its dimness.

Cave Nebula, Sharpless 155 (Sh2-155)
In constellation Cepheus

Image in mapped colors from the light emitted by ionized elements. 
Red=Sulfur, Green=Hydrogen and Blue=Oxygen.

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. 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.

Orientation in a wide filed image

Area of interest is marked as a white rectangle. More info about this image HERE.
An apparent size of the full Moon is marked at the lower right corner for a scale.
Click for a large image.

Technical details:

Processing work flow:
Image acquisition, MaxiDL v5.07.
Stacked and calibrated in CCDStack2.
Levels, curves and color combine in PS CS3.

Optics, Meade LX200 GPS 12" @ f5
Camera, QHY9
Guiding, SXV-AO, an active optics unit, and Lodestar guide camera 8Hz
Image Scale, ~0,8 arc-seconds/pixel
15x 1200s exposures for the H-alpha, emission of ionized Hydrogen = 5h
Narrowband cahnnels for ionized Oxygen and Sulfur are taken from an older wide field image seen above.


A single 20 min. H-alpha frame
Calibrated with Bias corrected flat and Dark masters in CCDStack

1200 seconds of H-aplha light with 12" SCT @ f5 and QHY9 astrocamera.
Image is scaled down 50% from original.

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