Imaging telescopes or lenses: Planewave CDK24
Imaging cameras: FLI Proline 16803
Mounts: Planewave L600
Guiding cameras: Starlight Xpress Ultrastar
Focal reducers: None
Software: Sequence Generator Pro · Photoshop CS3 · PixInsight 1.8 · PHD Guiding 2 · CCDWare CCD Inspector · Planewave PWI4 · Planewave PWI3 · Maxim DL6
Filters: Astrodon 50 mm 5 nm Ha · Astrodon 50mm B · Astrodon 50mm R · Astrodon 50 mm 5 nm OIII · Astrodon 50 mm G
Accessory: FLI CFW-5-7 · Astrodon Monster MOAG · Hedrick Focuser · Planewave Delta-T · Planewave EFA
Dates:July 25, 2020 , July 26, 2020
Frames:
Astrodon 50 mm 5 nm Ha: 6x1800" -30C bin 1x1
Astrodon 50 mm 5 nm OIII: 8x1800" -30C bin 1x1
Astrodon 50 mm G: 8x900" -30C bin 1x1
Astrodon 50mm B: 8x900" -30C bin 1x1
Astrodon 50mm R: 8x900" -30C bin 1x1
Integration: 13.0 hours
Darks: ~40
Flats: ~100
Flat darks: ~100
Bias: ~20
Avg. Moon age: 5.73 days
Avg. Moon phase: 32.86%
Mean SQM: 21.50
Mean FWHM: 2.00
Astrometry.net job: 3711736
RA center: 19h 59' 35"
DEC center: +22° 43' 12"
Pixel scale: 0.234 arcsec/pixel
Orientation: -178.690 degrees
Field radius: 0.364 degrees
Resolution: 7926x7926
Locations: KG Observatory, Julian, CA, United States
Data source: Backyard
I hear it now... "KG, you forgot to remove the green!" (-:
My goal with this project was to see if I could reproduce the Dumbbell nebula "from core to wings" with the true colors I see in the stretched RGB.
Luckily skies were dark enough for me to see the faint wings in the RGB data. So that gave me a good color reference.
Creating the core in the spirit of the RGB with Ha and OIII was not too difficult. Here I screen Ha-OIII-OIII with hues of 0, 217, 119 and Lightness of -42, -53, and -69.
I then overlay Ha Luminosity at 40% opacity for Ha contrast.
Next up is the wings. They're extracted from Ha and OIII using the default PI stretch followed by several applications of HDR6G11 to tone down the core.
Starnet++ is then used to remove the stars. I then use shadows, denoise and a luminance mask to help extract the wings.
To match the Ha wing to what I see in the RGB, an Ha Lighten layer with 0 hue works well.
The OIII wing is a bit tricky. That required two screen layers with hue 217, 121 and lightness -60, -75.
Finally a Starnet++ RGB star mask is screened over the top to produce what might arguably be a "true color" Dumbbell Nebula. (-:
Here's all my capture references to help clarify some of the above thoughts...
Description: Subtracted the bright core from the wing layers. This allowed stretching the wings a bit more while still maintaining the core color and contrast.
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