The cosmic sea jellyfish in Sulfur ΙΙ, Oxygen ΙΙΙ and Hydrogen-α (SHO). The remnant of a dead star, a supernova that lit up the heavens 30,000 years ago.
Star alligment of the linear Ha, OIII and SII data using StarAllignment (Hydrogen-α frame as a reference).
Dynamic Crop on all frames using the same process.
Background Noise Resduction with Dynamic Background Extraction (using 50 points on non-nebula areas, separately for each frame).
The auto-stretch of the OIII frame (weaker emmision of all three) that performed with STF (ScreenTransferFunction) with unlinked RGB channels, was applied on both the Hydrogen-α and OIII frames using HistogramTransformation to balance the emissions.
Noise reduction was performed with MultiscaleLinearTransform to reduce the noise and prepare them for the Pixel Math process. 4 layers with the following settings (R as default):
Layer 1: Threshold 0.500, Amount 0.50, Iterations: 1
Layer 2: Threshold 0.500, Amount 0.50, Iterations: 1
Layer 3: Threshold 0.500, Amount 0.50, Iterations: 1
Layer 4: Threshold 0.500, Amount 0.50, Iterations: 1
The Pixel Math formula that was applied:
R: (0.76 * SII) + (0.24 * HA)
G: (0.85 * HA) + (0.3 * OIII) + (0.15 * SII)
The green was reduced with SCNR at 9.0, the red at 0.23 and green again at 0.23.
Further noise reduction was applied with ACDNR and StdDev of 1.0 and Amount 0.50.
Star Reduction was applied with StarMask at 0.04000 Noise threshold, Scale 6 and Structure Growth as 0, 1 and 2 (Large-scale, Small-scale and Compensation).
Curves Transformations were applied to boost RGB/K and Saturation.
Selective Sharpening with High Pass Filter (radius 1.6).
26th & 27th February, 25th, 28th March 2019, Bedworth, GMT+0, United Kingdom, Bortle Class 5 ~SGM: 19.57 mag./arc sec2
Camera: ZWO ASI 1600MM-PRO USB 3.0 Mono (Type CMOS)
Sensor Cooling Temperature: -15C
Filters: 1.25" 5nm Astrodon Ha, 1.25" 3nm Astrodon OIII, 1.25" 3nm Astrodon SII
Imaging Telescope: Takahashi FS-60CB
Correcting Lens: Takahashi Reducer 0.72x (composite focal length at 264mm and focal ratio at f/4.9)
Mount: iOptron CEM25EC
12Bit ADC (FITS)
50 x 180" Ha subs (Unity Gain, Gain: 139, Offset: 21, Binning 1x1)
42 x 180" OIII subs (Unity Gain, Gain: 139, Offset: 21, Binning 1x1)
42 x 180" SII subs (Unity Gain, Gain: 139, Offset: 21, Binning 1x1)
20 Darks, 20 Flats
PixInsight 1.8 Core