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Hemisphere:  Northern  ·  Contains:  B207
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LBN777 - Happy Lil' Ghost Nebula, 



    
        

            Jonathan W MacCollum
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LBN777 - Happy Lil' Ghost Nebula

Technical card

Imaging telescopes or lenses: Orion 203/1000 f/4.9

Imaging cameras: ZWO ASI183MM-pro

Mounts: Celestron CGEM

Guiding telescopes or lenses: ZWO OAG

Guiding cameras: ZWO ASI120MM

Software: PixInsight PinInsight 1.8.5  ·  Isbeorn N.I.N.A.  ·  PHD 2

Filters: Astrodon LRGB Tru-Balance I-Series Gen B  ·  Astrodon LRGB Tru-Balance I-Series Gen G  ·  Astrodon LRGB Tru-Balance I-Series Gen R  ·  Astrodon LRGB Tru-Balance I-Series Gen L

Accessory: Skywatcher 2" Coma Corrector f/4  ·  ZWO EFW 8 EFW 8x1.25" filter wheel


Frames:
Astrodon LRGB Tru-Balance I-Series Gen B: 73x120" (gain: 111.00) -15C
Astrodon LRGB Tru-Balance I-Series Gen G: 69x120" (gain: 111.00) -15C
Astrodon LRGB Tru-Balance I-Series Gen L: 300x120" (gain: 111.00) -15C
Astrodon LRGB Tru-Balance I-Series Gen L: 26x240" (gain: 111.00) -15C
Astrodon LRGB Tru-Balance I-Series Gen R: 80x120" (gain: 111.00) -15C bin 1x1

Integration: 19.1 hours

Darks: ~60

Flats: ~15

Flat darks: ~15

Bortle Dark-Sky Scale: 4.00


Astrometry.net job: 3318340

RA center: 4h 4' 23"

DEC center: +26° 19' 37"

Pixel scale: 0.498 arcsec/pixel

Orientation: 86.204 degrees

Field radius: 0.422 degrees


Resolution: 5226x3147

Data source: Backyard

Description

LBN777 - The Happy lil' Ghost Nebula

I first came across this target when imaging the dusty region between the Taurus Dark Molecular Cloud and the Pleiades with my 135mm camera lens in early 2019. I immediately saw what looked like a hybrid of the "Pacman" character of the late arcade game and one of the ghost within the game. To me it looks like a ghost-like pacman lurching forward mouth-open to consume that bright shiny yellow star. I have yet to process that widefield image to my satisfaction, but set a goal for myself late this season to try and capture it with my 8in Newt. Despite the large amount of integration time, I felt that it still just isn't enough to do it justice. There were after a number of false starts processing this data, but nontheless was a pleasure to work on this data seeing all of the wisps of dust in the lower right corner, and the small yet prominant galaxies throughout the field. The brightest star has what appeared to be some sort of reflection or halo going on, but turns out this is a real structure as it shows up in almost all images I've been able to find of this target. But here it is, I have finally reached a version I am fairly happy with and hope you do too. Constructive Criticism is highly encouraged as I hope to continue to improve my processing abilities. I have also acquired more widefield data of this region, and it's on my processing check-list. Perhaps with the recent decrees to "stay home" as people are reacting to the outbreak of COVID-19 I'll finally get to put a dent into my processing backlog.

Equipment:

Orion 8in F4.9 1000mm Newtonian Reflector

Flocked / Primary mirror replaced due to turned-down-edge

Skywatcher F4 Aplanatic Coma Corrector

Astrodon I Series L, R, G, B broadband filters

ASI183mm Pro cooled to -15C

Celestron CGEM Mount

Self tuned / hacks to get guiding stable include:

Intentional offset polar alignment so dec always pulses in one direction

Balance "west" heavy (rather than the recommended east) so that the ota "falls" onto the gear teeth rather than get "lifted"

Factor Reset hand-controller daily (to prevent cgem from being possessed and forgetting where the meridian is on subsequent night)

Dither in RA only

Acquisition Details:

Images captured using N.I.N.A

Red: 80x2min (+8 rejected)

Green: 69x2min (+17 rejected)

Blue: 73x2min (+11 rejected)

Lum: 300x2min (+57 rejected)

Lum: 26x4min (none rejected)

Total Integration Time: 19 hours 08 minutes

Imaging Dates: Data Captured over 9 Nights in late November and December 2019
2019-11-01 2019-11-02 2019-11-03
2019-11-20 2019-11-24 2019-11-25
2019-12-24 2019-12-25 2019-12-30

The resulting image is a combination of the following steps:

Inspected all 610 subs for bad images with Blink after each session, discarding those with clouds, or trailing stars from poor stars.

Calibrated all subs with their corresponding master flat and master dark

Used subframe selector to weight all remaining subs together using the following formula:

(15*(1-(FWHM-FWHMMin)/(FWHMMax-FWHMMin))

+ 25*(1-(Eccentricity-EccentricityMin)/(EccentricityMax-EccentricityMin))

+ 15*(SNRWeight-SNRWeightMin)/(SNRWeightMax-SNRWeightMin)

+ 20*(1-(Median-MedianMin)/(MedianMax-MedianMin))

+ 10*(Stars-StarsMin)/(StarsMax-StarsMin))

+ 25

Selected the best sub from subframe and blink to use as a reference frame in stacking

Created a super luminance by integrating all remaining 548 frames together

Integrated all Red frames together, Blue frames together and Green frames together to create masters for each color

Cropped the stacking edges of the integrated masters

Combined the Red, Green and Blue masters to create a color RGB image

Superluminance Processing:

Automatic Background Extractor

Function degree 1 with normalization

Independently produce a noise reduced image and a sharpened image

Two rounds of Noise Reduction was done using TGV Denoise with a low contrast mask and an autostretched local support (First round with very strong edge protection, second round with very weak edge protection but very small strength)

Deconvolution was done on a separate copy of the luminance with

No deringing

wavelet regularization with 5 layers and strong but reducing amounts/thresholds

A starmask was created from the Noise Reduction copy to replace the stars with the origional superluminance, eliminating the ringing artifacts from deconvolution as similarly documented by /u/OkeWoke

The noise reduced copy and the sharpened copy were combined using a luminance-based mask where the high-signal areas were filled in from the deconvolution copy and the low-signal areas were filled in from the noise reduction copy:
Decon*CombineMask+NR*~CombineMask

Masked Stretch was used with no clipping and a background reference created from 4 preview windows and the Preview Aggregator script. Histogram Transformation was used to bring the tail of the blacks in without clipping and perform additional lifting of the nebulosity..

Local Histogram Equalization was used to enhance the larger structures

The overall impact of the stars were reduced and star cores were shaped with two rounds of Morphological Transformation and a contours based mask created by subtracting the resulting image from an expanded starmask.

RGB Processing:

Automatic Background Extractor

Function degree 1 with normalization

Background Neutralization using 5 preview windows and the Preview Aggregator script as the background reference

Color Calibration using Photometric Color Calibration using the Average Spiral Galaxy as the white reference

Noise Reduction using TGV Denoise with a low contrast mask and an autostretched local support targetting luminance and chrominance

Noise Reduction using MMT with a very protective luminance mask targetting luminance and chrominance

Repair the saturated star cores with the HSV Repaired Separation script

Arcsinh Stretch and Histogram Stretch to bring to non-linear

SCNR Green on the background with a luminance mask

Additional curves transformation to increase overall color saturation

Final Steps:

The super luminance and the RGB image were then combined using the Channel Combination tool in CIE L*A*B mode to apply the Super Luminance to the RGB image

Curves Transformation to increase contrast and colors throughout the field

Final round of noise reduction with MLT to target the remaining small scale chrominance noise

ICC Color Profile was added and the image saved as PNG for viewing on the internet

Comments

Author

eigenVector
Jonathan W MacCollum
License: Attribution Creative Commons
3267
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Revisions

  • Final
    LBN777 - Happy Lil' Ghost Nebula, 



    
        

            Jonathan W MacCollum
    Original
    LBN777 - Happy Lil' Ghost Nebula, 



    
        

            Jonathan W MacCollum
    B

B

Description: Annotated

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Histogram

LBN777 - Happy Lil' Ghost Nebula, 



    
        

            Jonathan W MacCollum