Part of the massive nebulous region of gas and dust in the constellation of Cepheus the curled up cloud really seems to embody what is common name suggests. The whole region is catalogues as IC1396 and is a favourite of mine. It is not particular bright requiring several hours of imaging but it seems to really respond well to Post processing, possibly because the major areas of interests are the dark streaks of cloud that contrast so well with the overall nebulosity.
I imaged this back in November 2021 with the DSLR, the session turned into a processing experiment aiming to deliver practical examples of Quantity vs Quality of light exposures. You can see that post here.
New 533 MC Pro camera came out and with its smaller sensor size I was able to image much closer into the actual trunk.
I have 1 nights worth of data on this target on this image from around 1730 to 0000 starting on the 9th December. This unfortunately meant dealing with a full moon but I was keen to test the camera and picked this subject to be away from the brightest part of the sky, that said even with the magic of the L-Enhance filter it is far from ideal.
The nebulosity is 2,400 light years from earth, stars being formed within the trunk are very young, several thought to be 100,000 years old (for stars that can burn for billions of years it is very young).
Capture
2022-12-09
533MC Pro camera cooled to -10ºC gain 100 offset 40
71 Lights were taken exposed at 300s
30 Flats and 30 Dark flats
After removing 15 frames for being outside of good weights FWHM I was left with 56 frames
56*5m = 4h40m of exposure.
Post Processing
Siril
After registration of all images (before the selection of the best 25) I ran a background extraction process on all registered images using a simple 1-order Polynomial model (straightforward Siril option). This was performed as there was a significant moon that evening and the fact that a side of pier (east->west) was performed meant that background extraction did not work well on the final image.
Crop - minor to remove stacking artefacts
Colour Calibration Photometry
Deconvolution, Kernal size of 0.9
Asinh Stretch - 3 iterations with stretches of (30,10,2)
Histogram Stretch
Green Noise Removal
Starless and Stars created using Siril Pixel Maths and Starnet++.
Once we have a TIFF (16 bit version) of Starless move into PS.
Photoshop (PS) Processing
Levels & Curves
Raw - Highlights and Contrast
Raw - Texture
Raw - Clarity
Raw - Colour Contrast
Raw - Noise Reduction
Raw - Saturation and Vibrancy and Shadow
Create FIT version of TIFF file output from PS using Siril
Once back from PS then Pixel Math Add the Stars back into the FIT version of the PS processed TIFF file using the formulae (starless+stars)).
Created JPG version.
Conclusion
Damn the moon! Frustrating when we get so few clear nights and when we get them invariably there is Full Moon...I think without that moon shining there would undoubtedly have been more signal to work with as there is more noise which took a fair degree of Noise Reduction and Texture manipulation to hide as much as possible. That said I am happy to be outside with the new camera and will be returning to this object hopefully in the next few weeks to try and get a a full Moonless night on it.
ความคิดเห็น