M16 Eagle Nebula in HOS + RGB Stars (Aaron Freimark)

M16 Eagle Nebula in HOS + RGB Stars

M16, the Eagle Nebula, which includes the famous “Pillars of Creation.” 7.6 hours of data, from my driveway in Cold Spring

Preprocessing
1. Subframe Selector to find and remove subframes with eccentricity ≥ 0.7
2. WeightedBatchProcessing
3. Create preview to crop
4. DrizzleIntegration with Region of Interest to crop to preview
5. NoiseXTerminator

RGB
7. LinearFit R & B to G
8. ChannelCombination to create RGB
9. ImageSolver script
10. Photometric Channel Combination
11. Histogram Transformation to stretch, just a little, so that stars are just visible

Narrowband/HOS
12. StarXTerminator 1.3.1 on the linear images (works extremely well)
13. PixelMath to create HOS image: R: Ha / G: OIII / B: SII
14. Invert, SCNR green 50%, then invert again — this reduces the magenta cast
15. SCNR 100% to remove green
16. LRGB Combination to apply Ha as luminance, boosting saturation a bit
18. Range Mask to select brightest core
18. LRGB Combination to apply SII as luminance to the center, “reducing” the lightness slider to match background brightness in previews
19. Curves Transformation
20. Unsharp Mask

Combination
We now have a starless HOS and stars in RGB. The goal is to combine the two, but to have smaller stars within the nebula, and larger stars outside the nebula.
21. RangeMask on HOS image to select nebulosity
22. Invert mask so that we expose the nebula
23. PixelMath to multiply in the RGB stars: K: 1-((1-stars)*(1-$T))
24. HistogramTransformation on the stars to make them larger
25. Invert the mask on the combination image, to mask the nebula (which already has stars)
26. Apply the same PixelMath, to add the larger stars to the exterior to the nebula
27. Export to Photoshop and slightly adjust color balance

Mid-Hudson Astronomical Association (MHAA)
Northeast Imagers

	Distinct awarded users	Total awarded images
Image of the day
Top picks
Top pick nominations

	Image of the day	Top pick	Top pick nominations	Total submitted
Deep sky
Solar system
Extremely wide field
Star trails
Northern lights
Noctilucent clouds
Landscape

	Image of the day	Top pick	Top pick nominations	Total submitted
Backyard
Traveller
Own remote observatory
Amateur hosting facility
Public amaeteur data
Professional, scientific grade data
Mix of multiple sources
Other
Unknown

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Status	Advanced success
Started	...
Astrometry.net job	6186007
PixInsight job	BNNRNQGTG5B223EB250IADYXOM2WAEJO
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	18h18m49s.869
RA (top/left)	18h20m16s.409
RA (top/right)	18h16m24s.350
RA (bottom/right)	18h17m22s.965
RA (bottom/left)	18h21m15s.757

Dec (center)	-13°52′05″.54
Dec (top/left)	-13°22′27″.44
Dec (top/right)	-13°44′00″.31
Dec (bottom/right)	-14°21′41″.62
Dec (bottom/left)	-14°00′04″.99

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