M99 - The Coma Pinwheel Galaxy in Coma Berenices

Since I've been integrating many shorter exposures I wanted to see how drizzling a small ROI of my sensor would turn out at 3x. This image was completely processed from scratch at this resolution. I'll be processing the full image at a later date.

**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: 468x60s taken across two nights in late March and Early April 2019 (7hr 48min total integration)

* Flats: 20x3s at dusk calibrated with dark flats

* Darks: 60x60s at -10C

* Bias: None

* Bortle Dark-Sky Scale: 4.00

* Pixel scale: 0.981 arcsec/pixel / 3x (from drizzle)

* Orientation: 182* 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 468 of 468 frames selected using a combination of Blink Subframe Selector

* Weighting:

```

20*(1-(FWHM - FWHMMin) / (FWHMMax - FWHMMin))

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

+ 30*((SNRWeight - SNRWeightMin) / (SNRWeightMax - SNRWeightMin))

+ 30

```

* No Local normalization reference

* CFA drizzled 3x with ROI around M99

* Crop with Dynamic Crop

* Dynamic Background Extraction

* Background Neutralization

* Photometric Color Calibration

* RGB Working space to 1,1,1

**Extract synthetic L for Deconvolution**

* Deconvolution with a Dynamic PSF L |> select 16 samples from middle of image |> Export PSF

* No De-ringing

* 5 layers of Gaussian wavelet regularization (Thanks burscikas for the assistance on this alteration to my normal aproach)

* Use clone stamp to create a star-mask for replacing the stars and replace these stars by applying the origional non-deconvolved Luminance over-top with pixelmath

**Extract synthetic L for Noise Reduction**

* TGV Noise reduction Using a low contrast mask

* MMT Noise reduction using 8 layers and a very protective luminance mask

**Combining Sharpened L, NR L and Stretching Luminance**

* Pixel Math with luminance-based mask to apply Deconvolution image only to the non-background areas of the Noise Reduced L

* Stretch with Histogram Transformation

* Mid-stretch noise reduction with ACDNR

**RGB workflow:**

* Small Scale noise reduction using TGV Denoise

* Chrominance Noise reduction using MMT

* Stretch with Histogram Transformation

* Mid-stretch noise reduction with ACDNR

* Curves to drop saturation in background

* LRGB Combination

* Enhance contrast in M99 with HDR Multiscale Transform with a Galaxy-Only covered mask: 7 layers and median transform to lightness with lightness mask checked

* Final Histogram Stretch

* Cleanup noise artifacts in brighter stars with star mask and light convolution

* Save as JPEG