Whoop, look at this! Winter is coming here in Saudi Arabia, and the seeing conditions are improving. Especially here on the shores of the Red Sea, it's often quite challenging: high temperatures, dust, humidity, and wind are not the best friends of the astrophotographer. However, I collected for the first time data of NGC1499, aka the California Nebula. This is a target that I had never focused on before, but one of the latest YouTube videos from "Cuiv, The Lazy Geek" was a real eye-opener, and I had to try it myself. Good decision, I would say 😉
—I documented my workflow. Maybe it's useful information:
OSC with L-eNhance filter (Ha, OIII), camera cooled to -5°C (ambient T was between 24°C and 28°C)
37x 600 sec over two nights (my balcony faces west, so I could only start on this target after it crossed the Meridian)
50 flats, 50 darks, 118 bias
- PixInsight WeightedBatchPreprocessing Script for calibration, stacking, and (2x)drizzle integration
- Open the Drizzle Master and do a very slight DynamicCrop
- Dynamic Background Extraction (tolerance 3, smoothing factor 0.6, sample size 30)
- EZ Soft Stretch (default settings)
- Resample 50% (because of the 2xdrizzle)
- Clone and remove stars with StarXTerminator (Generate Star Image, Unscreen Stars)
- Starless Image: Normalize HOO data with Pixelmath (Script by B. Blanshan)
- Starless Image: NoiseXTerminator (Denoise 65, Detail 55)
- Starless Image: create, blur and apply Yellow Mask (Script by B. Blanshan)
- Starless Image: Curves run 1, significantly raise red, slightly raise green, raise saturation and give RGB a slight S-curve; tweak Red, Green, and Saturation a bit more after the first adjustments were applied
- [color=var(--lighterGrey)]Starless Image: create, blur, and apply Blue Mask (Script by B. Blanshan)[/color]
- Starless Image: Curves run 2, raise Blue and Saturation, raise a bit Green and Lightness, RGB slight S-curve; after applying the first adjustments, slightly tweak blue and green, reduce red a little bit
- [color=var(--lighterGrey)]Extract Lightness from Starless Image, create and apply a mask from it (Histogram Transformation and Blur)[/color]
- Curves Run 3, tweak RGB (S-curve) and Saturation of the Nebula
- Invert the Lightness mask and de-emphasize a bit the darks of the background (asymmetric S-curve)
- [color=var(--lighterGrey)]Starless Image (with Lightness mask): 2 runs of LocalHistogramEqualisation; first for larger structures with Kernel Radius 120, Amount 0.45); second for smaller structures with Kernel Radius 50, Amount 0.4)[/color]
- Starless Image (with Lightness mask): HDRMultiscaleTransform (Number of Layers 8)
- Starless Image: remove the mask and Improve Brilliance (Script by J. Terpe); Brilliance set to 0.75, Improve Contrast Edges checked
- Stars (generated from StarXTerminator): SCNR, Remove Green (amount 0.85)
- Recombine the starless image with stars; Pixelmath: ~((~Starless)*(~Stars))
- Star Reduction using PixelMath (Script by B. Blanshan, Halo Method - V2), set S-value to 3
- [color=var(--lighterGrey)]Save Starless and Combined as 16bit Tiff files and hand them over to Photoshop for some further tweaking[/color]
- Photoshop: slight basic adjustments in Camera RAW
- Photoshop: last noise reduction with NoiseXTerminator (Denoise 40, Detail 25)
- Photoshop: Make the coolers a bit more pop via Curves in LAB color space (give channels "a "and "b "a slight S-curve and adjust the layer opacity)
Done!
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