**NGC 7023 - Iris Nebula**

**Equipment:**

* Orion 8in f4.9 1000mm Flocked / replaced GSO primary mirror

* Guiding with ZWO OAG and asi178mm camera

* ASI071mc one-shot-color cam

* Hutech IDAS LPS D1 Filter

* Celestron CGEM Mount

**Acquisition:**

* Lights:

97x120.0s at -10C on 2019-07-24

* Flats: combination of sky flats and ceiling flats for each session

* Darks: 60x120s at -10C

* Bias: None

* Bortle Dark-Sky Scale: 4.00

* Pixel scale: 0.981 arcsec/pixel

* Orientation: 0 degrees

**Pre-Processing with PixInsight:**

* Calibrated and stacked using [LVA PreProcessing Steps](http://www.lightvortexastronomy.com/tutorial-pre-processing-calibrating-and-stacking-images-in-pixinsight.html)

* Integrated best 97 of 121 frames selected using a combination of Blink Subframe Selector

Processing Steps:

I've decided my processing workflow may be best summarized with pseudocode:

```F#

/// Pre Processing

let rgb =

Image Integration

|> Dynamic Crop

|> Dynamic Background Extraction

|> Background Neutralization <| (4 Previews |> Preview Aggregator)

|> Color Calibration

|> Image Solver

|> Photometric Color Calibration

|> RGB Working Space <| (1,1,1)

/// Synthetic Luminance

let l_orig =

rgb

|> extract synthetic luminance

/// Background Noise Reduction

let l_nr =

l_orig

|> Tgvnr // Small Scale Noise Reduction

|> Mmtnr // Large Scale Noise Reduction

/// High-Signal Sharpening

let l_sharpen =

l_orig

|> Deconvolution // 5-layer regularization no deringinging

|> Replace stars <| star mask <| l_orig

|> Mmt sharpen

/// Prepare mask for combining Low-Signal background with High Signal Foreground

let l_combine_mask =

l_nr

|> stf

|> hist stretch cliping whites and blacks

|> blur

/// Combine Low-Signal background with High Signal Foreground

let l =

l_sharpen*l_combine_mask + l_nr *~l_combine_mask

|> curves for contrast enhancement

/// RGB cleanup and combination

let final =

rgb

|> scnr green

|> Tgvnr // Small Scale Noise Reduction

|> Mmtnr // Large Scale Noise Reduction

|> Additional round of DBE and SCNR

|> HSV Repair Separation Script

|> Arcsinh Stretch

|> lrgb combination(l)

|> histogram transfromation

|> cleanup artifacts from hotpixels with clonestamp

```

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