Hi All,
They’re few and far between, but I’m pleased to present my latest effort;
IC1848 – The Soul Nebula.
The faint emission nebulae and overlapping open cluster of IC1848 resides in the constellation Cassiopeia. It is commonly known as the Soul or Baby nebulae, due to the nebulosity displaying the contours of what appears to be a foetus. The nebulae glows vibrantly red due to energised hydrogen. Present near the top of the foetus head is the bright nebulae IC1871, while the open cluster dots the foetus stomach. The nebulae is estimated as being 6,500 light years distant.
The image is an [LHa][RHa]GB composite.
About the image;
The final image is an [LHa][RHa]GB composite with a total exposure time of 5 hours (L:90min, Ha:60min, R:50min, G:50min, B:50min). The data was collected over a couple of nights due to bad weather. Beginning to understand the colour balance output of the Astrodon filters, but still not really comfortable with them. I like the clean R channel that comes with the Custom Scientific filter set. I feel the colour balance is quite accurate despite the complexities of integrating rich Ha data that attempts to throw the balance out. More data would have reduced the noise associated with the Ha data. The knots of dark nebulae contrast well with the red nebulosity. May reprocess using a few different methods given time.
Image Processing;
All light subs dark, flat and bias calibrated in MaximDL and registered in Registar. Combined in MaximDL using RC Sigma Reject. Luminance data pushed through two iterations of deconvolution using CCDSharp. The Ha data was not deconvoluted in order to maintain maximum nebulosity. Files converted to tiffs for PS work that follows;
The “super” luminance layer was created in PS using a blend of Ha 70% and luminance at 30% and initially stretched using DDP back in MaximDL. To avoid the typical salmon pink nebulosity when integrating Ha data I created a super R channel using the Ha data. The Ha data blended into the R channel at 40% which brought out the typical vibrant nebula emission line. This process was trial and error. A too strong blend resulted in major work rebalancing. The new R channel was then recombined with G and B channels to created a new [RHa]GB blend. While this process assisted in producing a rich nebula colour, it throws the star colour balance out significantly. To counter act this, I layered the base RGB (no Ha blending) composite using a layer mask to “bring back the stars”. This allows for a more aesthetic looking result. Chrominance data was stretched using shadow/highlights tool to obtain better control of colour saturation as the non-linear stretch was performed. All three layers, LHa, RHaGB and RGB (stars) were then combined and manipulated in PS. A nasty red gradient was present due to a poor flat field which needed some corrections, but overall the data was rather gradient free (sigh of relief). A couple of layer masks were also created – colour noise reduction and selective contrast enhancements (for details). Concluded with minor colour balance tweaks before flattening.
Thanks for looking!
I hope you enjoy it.
As usual, all comments welcome.
Cheers