The Cat's Paw Nebula is an emission and star forming region in the constellation Scorpius. It was a very low target for me as I am shooting from 34°N, the target never rose above 21°. The RGB frames were also shot through a thin layer of clouds. This is my first light with the new camera, I'm super pleased with the results given the low integration time and position of the target!

Equipment:

OTA: William Optics GT81 w/0.8x reducer (382mm fl at f/4.7)

Mount: Orion Sirius EQ-G (HEQ-5)

Guidescope: Orion 50mm guidescope

Guiding camera: Orion StarShoot Autoguider

Imaging camera: ZWO ASI1600MM-Cool

Software:

SGP

PHD2

CdC

PixInsight

Acquisition:

Location: Atoka, Oklahoma (Bortle 3)

Dates: 5/24/17, 5/29/17

Gain: 0 Offset: 10

Camera temp: -20C

L: 38x180"

R: 8x180"

G: 8x180"

B: 8x180"

Total integration time: 3hr 6min

60x darks

30x flats per filter

200x bias (master bias in library)

Preprocessing:

Batch PreProcessing script to generate calibrated/registered images

ImageIntegration (Linear Fit rejection for L, Percentile rejection for RGB)

Dynamic Crop the masters

DBEx2 on each master

RGB processing:

LinearFit to Red channel

ChannelCombination to combine

BackgroundNeutralization

ColorCalibration

SCNR green

TGV and MMT noise reduction (via Jon Rista's method)

SCNR green

HistogramTransformation x3

CurvesTransformation w/starmask to saturate stars

CurvesTransformation w/~starmask to saturate nebulosity

CurvesTransformation w/Lmask(minus stars) to further saturate nebula

CurvesTransformation for contrast

SCNR green

L processing:

Deconvolution

MMT (slight NR)

HistogramTransformation x3 using a starmask to manually perform a masked stretch

CurvesTransformation small stretch

Duplicated the image to create a starless version, using a starmask and several iterations of MMT and MT. Then pushed the faint nebulosity in the starless version using PixelMath expression: "1-(1-$T)*(1-$T)"

Combined the starless version with the image using PixelMath expression "F=0.4; (1-(1-$T)*(1-s)*F)+($T*~F)" followed by the same function but with a value of F=0.2. (s=starless photo).

HistogramTransformation to move black point

LocalHistogramEqualization with inverted starmask

CurvesTransformation for contrast

MorphologicalTransformation for star reduction

Combined L and RGB with the script "LRVB-AIP"

SCNR red with starmask to dim annoyingly bright red stars

SCNR green

CurvesTransformation for slight contrast

HistogramTransformation to bring the green channel in just a tad because the image was too red.