**NGC 4236**

**Equipment:**

* Orion 8in f4.9 1000mm / Flocked / Mask on Turned down edge on primary

* Guiding with ZWO OAG and asi178mm camera

* ASI071mc one-shot-color cam

* Hutech IDAS LPS D1 Filter

* Celestron CGEM Mount

**Acquisition:**

* Lights:

163x120.0s at -10C on 2019-03-06

235x120.0s at -10C on 2019-03-11

003x120.0s at -10C on 2019-03-28

390x060.0s at -10C on 2019-03-28

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

* Darks: 60x60s at -10C

* Darks: 60x120s at -10C

* Bias: None

* Bortle Dark-Sky Scale: 4.00

* Pixel scale: 0.981 arcsec/pixel / 2x (from drizzle)

* Orientation: 187 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 751 of 792 frames selected using a combination of Blink Subframe Selector

* Weighting:

```

10*(1-(FWHM - FWHMMin) / (FWHMMax - FWHMMin))

+ 45*(1-(Eccentricity - EccentricityMin) / (EccentricityMax - EccentricityMin))

+ 35*((SNRWeight - SNRWeightMin) / (SNRWeightMax - SNRWeightMin))

+ 30

```

Processing Steps:

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

```F#

/// Pre Processing

let rgb =

Image Integration

|> Drizzle Integration (CFA, Scale 2.0, Drop Shrink 0.7)

|> 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_orig

|> l_nr (inverted l_combine_mask)

|> l_sharpen (l_combine_mask)

|> Histogram Transformation // Stretch to non-linear

|> Local Histogram Equalization <|

mask((l_combine_mask-star_mask)|>convolution))

/// RGB cleanup and combination

let final =

rgb

|> tgvnr

|> mmtnr

|> shrink stars

|> histogram transfromation

|> lrgb combination(l)

|> curves to boost contrast and saturation

|> cleanup artifacts in brighter stars

```

* Save as JPEG