Cave Nebula / Sh2-155

Here an image of the Cave Nebula, catalogue reference Sh2-155, an emission nebula in the constellation of Cepheus. It is embedded in a larger region containing emission, reflection and dark nebula. The brightest part of the nebula has an apparent magnitude of 7.7, being situated about 2400 ly from Earth. The somewhat unusual rendition shown here is derived from 6 filters in total: Hydrogen-alpha, sulphur-II and oxygen-III ultra-fast narrowband filters and g´, i´, and z-s´ photometric filters. The g´ filter (400-550nm) captures nicely the reflection nebula, whilst the i´ (700-845nm) and z-s´ (820-920nm) filters transmit infrared light at different wavelengths. The data from these two filters then needs to be colour-mapped to a visible region of the spectrum. The following colour mapping has been applied to create this particular image: g´ mid-blue, O-III cyan, Ha yellow, S-II sunset orange, i´ crimson, z-s´ purple. Stars are from the monochrome S-II integration.

 

Calibration, Registration, Integration in APP, further processing to taste in PS.

 

The viewing conditions were not as good as was hoped (Rhön, Germany) with intermittent thin cloud and dew that fell with a particularly heavy "thud" 😉 , still most of the data was usable ...

 

Total time: 11.5 hrs / ISO 400

 

Celestron RASA11

10Micron GM1000 HPS

SIGMA fp L (monochrome)

Baader ultra-fast narrowband and SLOAN/SDSS photometric filters

Done