Ha: 10.08.2022, 11.08.2022
OIII: 20.08.2022

ZWO ASI 1600 MM Pro @ -20°C (Gain=139, Offset=21)
+ C14 & Starizona Hyperstar @ 675 mm (f/1.9)
+ Baader 2" Ha, OIII filter
+ Celestron EF
+ Tempest Cooler
+ Omegon Dew Heater
+ Astrozap Dew Shield for C 14 Hyperstar
on CGE-Pro mount

Cable managment to mitigate diffraction spikes.

Autoguiding:
Artesky 70 mm Guidscope (f=400 mm)
ZWO ASI 120 MM mini
PhD2 (Multistarguiding)
Dither

light frames:
203 x 120 s = 6h 46m (Ha)
249 x 120 s = 3h 44m (OIII)

dark frames:
30 x 120 s per channel (Ha & OIII)
60 x 30 s per channel (RGB)

acquired with N.I.N.A.

Remaining Issues
- RGB data required to replace HOO stars

Post-Processing

PixInsight
Ha, OIII channel (linear stage):
Manually blink and reject bad subs, subframeselector with eccentricity <= 0.7, WBPP script, NSG script, image integration, automatic background extraction, linear fit of Ha wrt OIII image, creation of HOO image by channel combination, Darkarchons EZ Processing Suite: EZ Denoise, EZ Softstretch

HOO processing (non-linear stage):
HOO star removal with StarNet2,  remove green tint using SCNR (minimum neutral, amount = 0.3), protect NGC6888 by luminance mask, enhance fainter nebulae in the background and improve contrast by histogram and curves transformation, slight color saturation enhancement by curves transformations, invert luminance mask to work on NGC6888, apply HDRMT with 7 layers to equalize the brighter and fainter parts of the nebula and reveal smaller details in the brighter parts, improve contrast and color saturation by curves transformation

Further contrast enhancement techniques based on the PixInsight Fundamental Videos for NGC 3486 (2021 version) by Adam Block

create range mask for NGC 6888, apply LocalHistrogramEqualization (amount=0.25) to NGC6888, remove range mask

HOO_MMT = MMT with Bias = 0.1 on layer 4

create new HOO_new = max(HOO_MMT,HOO)*.75 + min(HOO_MMT,HOO)*.25

Blend script: create new image Soft_light = Softlight of HOO_new with itself, apply luminance mask to HOO_new, create new image HOO_softlight = combination of Soft_light with luminance masked HOO_new image with PixelMath

Sharpening of L
enhanced luminance sharpening using this video by VisibleDark based on this tutorial on chaoticnebula.com

Topaz Denoise AI
Remove short-wavelength noise from starless image:
Low Light Mode On
Sharpen: 0
Remove Noise: 5

PixInsight
add HOO stars with Pixelmath, slight color saturation enhancement using curves transformation, star mask, enhance color saturation of stars by curves transformation, DarkStructureEnhance script (amount=0.4)

Adobe Lightroom
final adjustment: contrast, light, white, black, clarity, dynamic, saturation, HSL red & blue saturation and luminance enhancements