Celestial hemisphere:  Northern  ·  Constellation: Cygnus (Cyg)
Wolf Rayet 134, Jonathan W MacCollum
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Wolf Rayet 134

Wolf Rayet 134, Jonathan W MacCollum
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Wolf Rayet 134

Equipment

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Acquisition details

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Description

When imaging the [region in Cygnus around the Tulip Nebula](https://www.astrobin.com/422359/D/?nc=user) earlier this summer with my

135mm lens I came across this Blue Streak of Oiii data. I uploaded it hoping someone might comment on what it

was, when suddenly it seemed quite a few people on astrobin were also imaging it... turned out to be the

Wolf-Rayet 134 nebula. Inspired by so many on astrobin and including Chuck's [awesome video](https://youtu.be/Tbn5v13H5ko)

of him shooting this target, I too had to give it a go and suggested it as an option in the upcoming /r/astrophotgraphy OOTM.

Luckly /u/NGC6960 (the winner of last month's OOTM on /r/astrophotograph) ended up picking it for this month! So here is my attempt.

It's the first narrowband image that I have taken at this image scale (non wide-field) so I spent extra time for good measure.

Please let me know what you think of it and if there are specific areas I should look out for to improve in the future!

Equipment:

* 8in f4.9 Newtonian Reflector w/ Sesto Senso Auto Focuser

* Skywatcher Quattro Coma Corrector

* ZWO EFW

* Astrodon LRGB Filters + 3nm Oiii and 5nm Ha

* ZWO ASI 183mm Pro - Cooled to -15.0C

* Celestron CGEM Mount

* Dew Strips around the Primary mirror and Focuser draw tube

Integration/Acquisition Time per Channel:

* R: 20 / 29 x 60s (.3 hrs)

* G: 21 / 30 x 60s (.3 hrs)

* B: 20 / 29 x 60s (.3 hrs)

* Ha: 101/127 x 240s (6.7hrs)

* O3: 103/131 x 240s (6.9hrs)

Total acquisition time: 18 hours 40 minutes

Total rejected frames: 04 hours 03 minutes (removed mostly bloaded and elongated stars from poor guiding)

Total integration time: 14 hours 37 minutes

Data Taken across 5 nights: Sep 1st-Sep 7th

Guiding averaged ~0.9"/px RMS across all nights; Image Scale: 0.5"/px

Flats: 20/filter Calibrated Dark Flats;

Darks: 60/120s @ -15.0C

Bias: None

A superluminance was created by

* Integrating all images with

* Linear Fit Clipping

* Sigma High=9.0

* Sigma Low=9.0

* Drizzle Integration with

* Scale: 1x

* Drop shrink: 0.7

* Kernel Function: Var k=1.5

Luminance Processing (with Super Luminance):

* Crop edges

* No DBE: integrated data felt free of gradients so I skipped this entirely: From a Bortle 4 pointing straight at zenith under little-to-no moon still seemed odd.

* Deconvolution

* Using a dynamic PSF created with 60 stars from around the whole image

* Iterations: 60

* No Deringing

* 5 Layer Gaussian Wavelet Regularization with noise thresholds (12,10,8,5,3) and reduction (0.8,0.8,0.6,0.6,0.3)

* Filled in the ringing left behind with PixelMath ``L_Orig`` and a star mask created by ``L_Orig |> Histogram Stretched |> Starnet in StarMask mode |> MT Maximize |> Convolve``

* One round of gentle noise reduction using TGVDenoise using

* STF for Local Support

* Low Contrast mask

* Stretched a second copy using the Histogram Transformation with STF after shifting the white point to a desirable place

* Created previews around 4 background regions to make a background reference for Masked Stretch

* Masked Stretch

* 1000 iterations

* Used the median of the STF copy's background reference as target

* Created a preview aggregator from the same background references on the target image for stretching

* Histogram to bring the black point in without clipping

* Repeat Masked Stretch a second time

* Blend the Histogram Stretched copy (33%) with the Masked Stretch copy (66%) using PixelMath

* Final luminance smoothing using ACDNR

* StDev 0.8

* Amount: 0.23

* Iterations: 5

* With Luminance Mask enabled

* Remaining: Defaults

Narrowband Processing:

* Stacked each Ha and Oiii images separately using Linear Fit

* Cropped edges using the same Dynamic Crop process from Luminance

* Noise Reduction:

* Small scale TGV

* Stretched with Histogram Transformation

* Additional ACDNR noise reduction on Oiii

RGB data was taken purely to for it's star color

Each color channel was stacked by

* Integrating all images with

* Linear Fit Clipping

* Default rejection settings

* Drizzle Integration with

* Scale: 1x

* Drop Shrink: 0.9

* Kernel Function Var k=1.5

* Crop edges

* Fairly aggressive TGV and MMT Noise Reduction

* Repair blown out star color with the HSV Repair Separation script and Channel Combination

* Stretch with ArcsinhStretch and Histogram Transformation

* Final round of ACDNR Noise Reduction

Combined and Final Touches:

* The Ha and Oiii narrowband data was combined using the following formula:

* Red = Ha

* Blue = Oiii

* Green= ``iif( Ha > .50, 1-(1-Oiii)*(1.5-Ha), Oiii*(Ha+0.5) )``

* LRGB Combination to apply the processed Luminance data with this Narrowband data color image

* Star color was replaced using LRGB Combination of the RGB Stars data and a Star Mask created from the luminance of the previous results

* Oiii enhancements on the final color image:

* Oiii mask = ``((Oiii|>starnet) - (Ha|>starnet) - starmask)|>convolution 1.5``

* Local Histogram Equalization and slight Color Saturation boost

* Ha enhancements on the final color image:

* Ha mask = ``((Ha|>starnet) - (Oiii|>starnet) - starmask)|>convolution 1.5``

* Local Histogram Equalization and slight Color Saturation boost

* Final gentle touch of noise reduction using ACDNR

A starless version was created with Starnet++ (before combination and then recombined the same as above) with residual diffraction spikes and glow cleaned up using Affinity Photo's Inpaint brush.

Comments

Revisions

  • Wolf Rayet 134, Jonathan W MacCollum
    Original
  • Wolf Rayet 134, Jonathan W MacCollum
    B
  • Wolf Rayet 134, Jonathan W MacCollum
    C
  • Final
    Wolf Rayet 134, Jonathan W MacCollum
    D

B

Description: Starless

Uploaded: ...

C

Description: Oiii Data - Starless

Uploaded: ...

D

Description: Complete re-process of superluminance and recombination using HOO blend (no RGB stars)
R=Ha
G=50% Ha / 50% Oiii
B=Oiii

Included gentle HDR Transformation and Local Histogram Equalization on luminance

Uploaded: ...

Sky plot

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Histogram

Wolf Rayet 134, Jonathan W MacCollum