I've been planning on shooting M16 in SHO for over a year now. I decided to wait until I could acquire a Sii filter, which wasn't until early April. I also wanted to total 20+ hours on this before moving home and graduating college, which I got fairly close to thanks to online classes and no sleep schedule. In order to maximize the amount of time I could get on it, I began shooting from once it hit 20 degrees altitude until the end of nautical dark (average of 2.5 hours per night). Also made a [cropped comparison to Hubble's Pillars of Creation image](https://i.imgur.com/pmmQS10.jpg) as well as a [starless version](https://i.imgur.com/7RsGH1w.jpg). Captured on the nights of March 31, and April 2, 5, 15, 20, 21, and 24 from my apartment roof in Athens, GA (Bortle 7 zone).

**[Equipment:](https://i.imgur.com/BYyK1wu.jpg)**

> TPO 6" F/4 Imaging Newtonian

> Orion Sirius EQ-G

> ZWO ASI1600MM-Pro

> Skywatcher Quattro Coma Corrector

> ZWO EFW 8x1.25"/31mm

> Astronomik LRGB+CLS Filters- 31mm

> Astrodon 31mm Ha 5nm, Oiii 3nm, Sii 5nm

> Agena 50mm Deluxe Straight-Through Guide Scope

> ZWO ASI-120MC for guiding

> Moonlite Autofocuser

**Acquisition:** 18 hours 12 minutes (Camera at Unity Gain, -20°C)

> Sii- 61x360"

> Ha- 60x360"

> Oiii- 61x360"

> Darks- 30

> Flats- 30 per filter

**Capture Software:**

> Captured using [N.I.N.A.](https://nighttime-imaging.eu/), EQMod mount control, and PHD2 for guiding and dithering.

**[PixInsight Processing:](https://i.imgur.com/QyShtUy.png)**

> [Blink](https://youtu.be/sJeuWZNWImE?t=40)

> BatchPreProcessing

> StarAlignment

> ImageIntegration

> DrizzleIntrgration (2X, VarK 1.5)

> DynamicCrop

> AutomaticBackgroundExtraction (function degree: 1, division mode)

> Duplicated Ha to act as **Luminance**

**Luminance Processing:**

> Deconvolution

> PixelMath to add back in pre-decon stars

* Decon+star restoration method similar to the one outlined in [OkeWoke's tutorial](https://www.youtube.com/watch?v=6Maq-UkeqG8)

> TGV/MMT Noise reduction

* [Jon Rista noise reduction tutorial](https://jonrista.com/the-astrophotographers-guide/pixinsights/effective-noise-reduction-part-2/)

> ArcsinhStretch

> HistogramTransformation

**Individual Sii, Ha, and Oiii channel Processing:**

> ChannelCombination (SHO mapped to RGB, respectively)

**SHO Processing:**

> Unlinked STF applied via HistogramTransformation

> LRGBCombination with nonlinear Lum (chrominance noise reduction enabled)

> Invert > SCNR > Invert (repeated twice)

* This removes a magenta cast common on Hubble palette images

> SCNR

* Removes some of the overwhelming green. Ha has the strongest signal and was initially mapped to the green channel.

> Several [Curve](https://i.imgur.com/pRWbYZD.jpg)Transformations for lightness, saturation and color adjustments (mostly red and green channels)

* Star mask

> HDRMultiscaleTransform

* Helps bring out the pillars in the brighter core region

> More curves for color tweaking nebula and stars

> Invert > SCNR > Invert with a star mask

* This was to reduce the magenta stars common in Hubble palette images. I opted to preserve some of the magenta stars in the core to better match the look of the 2014 HST image of the pillars

> HistogramTransformation to slightly boost red channel

> DarkStructureEnchance

> Invert > SCNR > Invert again to tweak overall magenta color

> ACDNR

* Nonlinear noise reduction

> LocalHistogramTransformation

* Boosts contrast, especially in the core region

> More curves with range mask

* tweaking core region colors

> MorphologicalTransformation to reduce star sizes

> More curves for more color tweaks

> ACDNR

* Final noise reduction tweaks

> One last curve transformation to tweak green channel

* I ended up doing a lot of my nonlinear processing with the green channel adjusted via STF, and didn't realize until the very end. Forgot to save the original STF process, so I tried to replicate it as best I could using curves

> Resample to 85%

> Annotation