**M3 - Globular Cluster in Canes Venatici**

Taken on a moon-lit night in March I bring you M3: a Globular Cluster in the constallation Canes Venatici. As always, feedback and constructive criticism on the image is encouraged!

**Equipment:**

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

* Guiding with ZWO 60mm f4.6 guidescope and asi178mm camera

* ASI071mc one-shot-color cam

* Hutech IDAS LPS D1 Filter

* Celestron CGEM Mount

**Acquisition:**

* Lights: 284x30s taken on the night of 2019-03-18

* Flats: 30x0.84s using t-shirt flats pointing at ceiling

* Dark Flats: 30x0.84s Same orientation as Flats with lid and jackets covering Optical Tube.

* Darks: 60x30s at -10C

* Bortle Dark-Sky Scale: 4.00

* Pixel scale: 0.981 arcsec/pixel

* Orientation: 9* 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 the best 284 out of 296 frames after sorting them through Blink and Subframe Selector.

* Weighting Expression

0*((Stars - StarsMin) / (StarsMax - StarsMin))

+ 05*(1-(FWHM - FWHMMin) / (FWHMMax - FWHMMin))

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

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

+ 30

* No local normalization

* CFA drizzled 1x scale 0.7 drop shrink

* Crop with Dynamic Crop

* Dynamic Background Extraction

* Background Neutralization

* Photometric Color Calibration

* RGB Working space to 1,1,1

**Luminance Processing**

* Extract Synthetic Luminance for Deconvolution

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

* Starmask for local support 0.3

* Global Dark: 0.0080

* Global Bright: 0.0010

* 3 layers of Poisson wavelet regularization

* Fix 1 brightest star cores that deconvolution introduced internal rings on by replacing them with the non-deconvolved image (clone stamp to create mask of the broken stars + pixel math ``L_Orig`` )

* Extract Synthetic Luminance for Noise Reduction

* Small Scale noise reduction using TGV Denoise

* Medium Scale Noise reduction using MMT

* Combine Decon image with NR image using a clipped and blurred luminance based mask and PixelMath ``L_Decon`` and ``L_NR`` with the mask inverted

* Stretch using masked stretch using a "Preview aggregator" of 5 different background previews as background reference.

**RGB workflow:**

* Small Scale noise reduction using TGV Denoise

* Medium Scale Chrominance Noise reduction using MMT

* Arcsinh Stretch to stretch non-linear

* Increase color saturation with a luminance mask

**LRGB Combination with 0.7 on L and 0.3 on saturation**

* Curves to enhance contrast raise background level and increase saturation

* Adaptive Stretch to push the background down without clipping data

* ACDNR to remove large scale chrominance noise in the background

* Save as JPEG