IC 5076

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August 21, 2022

IC 5076 is a reflection nebula located in Cygnus, not far from the bright star Deneb, and about 2 degrees north of the brightest part of the North America Nebula. It has been listed in several other catalogues, so it also identified as vdB 137, Ced 185, LBN 394 and more.  It was discovered by British astronomer Isaac Roberts in 1895. It is located approximately 5,700 light-years away in Cygnus. The stars around it belong to NGC 6991, an open cluster. The brightest star in the image is HD 199478 (also listed as a pulsating variable, V2140 Cyg). I find the brownish features along the right edge very interesting.

Acquisition, focusing, and control of Paramount MX mount with N.I.N.A., and TheSkyX. Focus with Optec DirectSync motors and controller. Equipment control with PrimaLuce Labs Eagle 4 Pro computer. All pre-processing and processing in PixInsight. Acquired from my SkyShed in Guelph. Very good transparency and average seeing. Acquired August 8-20, 2022 under a mostly Moon-free sky.

Sky-Watcher Esprit 150 f/7 refractor and QHY600M camera with Optolong UV/IR filter

Tak FSQ-106 @ f/5 (530mm), QHY-367C Pro One-shot colour with Optolong UV/IR filter 
210x5m Lum = 17hr30m
224x5m OSC = 18hr40m
Total: 36hr10m
Image scale 0.565 arcsec per pixel (Drizzled)
Finder Chart 

Data Reduction and Cleanup

The WeightedBatchPreProcessing script was used to perform calibration, cosmetic correction, weighting, registration, local normalization, integration and 2x drizzle integration of all frames.

The OSC master was aligned to the Luminance master with StarAlignment. This yielded aligned Lum and Colour masters.

DynamicBackgroundExtraction was applied to the Luminance and OSC masters.

Colour Calibration: ColorCalibration was used to calibrate the OSC master. 

Linear Noise Reduction: NoiseXterminator was used to reduce noise in the background areas with settings Amount=0.9 and Detail=0.35 

Stretching:  HistogramTransformation was applied to make a pleasing, bright image.

Deconvolution:  A star mask was made from the Luminance master to use as a Local Deringing Support Image. The GAME script was used to make a mask selecting only the nebula for deconvolution. Deconvolution was applied (40 iterations, regularized Richardson-Lucy, ParametricPSF mode with default settings; Global dark deringing = 0.04; Global bright deringing 0.003).

Linear Noise Reduction: NoiseXterminator was used to reduce noise in the background areas with settings Amount=0.9 and Detail=0.35

Stretching: HistogramTransformation was applied to make a pleasing, bright image. 

Combining Luminance and Colour Images
Luminance addition: LRGBCombination was applied to replace the lightness of the RGB image with the Luminance master.

Additional Processing
Star Removal:  StarNet v2 was used to remove stars.

Nonlinear Noise Reduction: NoiseXterminator was used to reduce noise in the background areas of each image with settings Amount=0.9 and Detail=0.25 

Contrast Enhancement: LocalHistogramEqualization was applied using an inverted lightness mask to protect the background and select the galaxies. Three passes were applied (scale 20, max contrast 1.5, strength 0.5, 1 iteration; scale 50, max contrast 1.5, strength 0.3, 1 iteration; and scale 100, max contrast 1.5, strength 0.25).

Sharpening: MultiscaleMedianTransform was used with the same mask used for Deconvolution to sharpen Layers 1 – 4 with strengths of 0.05, 0.2, 0.1 and 0.05, respectively.

Star Processing and Restoration: Curves was used to boost saturation in the stars. The stars were added back into the image using straight addition in PixelMath.

Final Steps: Background, galaxy and star brightness, contrast and saturation were adjusted in several iterations using CurvesTransformation with masks as required. MorphologicalTransformation was used in Morphological Selection mode to slightly reduce the size of stars.  ICCProfileTransformation (sRGB IEC61966-2.1; Relative Colorimetric with black point compensation) was applied prior to saving as a jpg.