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Contains:  M 20, M 21, NGC 6514, NGC 6531, Trifid Nebula
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M20 - Trifid Nebula - M21 Open Cluster - TS ONTC Newtonian - LHaRGB, 



    
        

            Rowland Archer
M20 - Trifid Nebula - M21 Open Cluster - TS ONTC Newtonian - LHaRGB
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M20 - Trifid Nebula - M21 Open Cluster - TS ONTC Newtonian - LHaRGB

Technical card

Imaging telescopes or lenses: Teleskop Service ONTC 8" Newton f4 (800 mm)

Imaging cameras: ZWO ASI1600MM-Cool

Mounts: iOptron CEM 60

Guiding telescopes or lenses: ZWO 60mm f/4.6 Guidescope

Guiding cameras: ZWO ASI 290 mini

Focal reducers: Televue Paracorr

Software: Adobe Photoship CC  ·  PHD2  ·  Astro Pixel Processor  ·  Starkeeper.it VOYAGER  ·  PixInsight 1.8 Ripley

Filters: Astrodon Red Tru-Balance E-Series Gen 2  ·  Astrodon Green Tru-Balance E-Series Gen 2  ·  Astrodon Blue Tru-Balance E-Series Gen 2


Dates:Aug. 9, 2020

Frames:
Astrodon Blue Tru-Balance E-Series Gen 2: 53x60" (gain: 139.00) -15C bin 1x1
Astrodon E-Series Tru-Balance [Lum]: 173x60" (gain: 139.00) -15C bin 1x1
Astrodon Green Tru-Balance E-Series Gen 2: 105x60" (gain: 139.00) -15C bin 1x1
Astrodon Ha 5nm: 91x120" (gain: 200.00) -15C bin 1x1
Astrodon Red Tru-Balance E-Series Gen 2: 9x60" (gain: 139.00) -15C bin 1x1

Integration: 8.7 hours

Avg. Moon age: 20.18 days

Avg. Moon phase: 70.31%

Bortle Dark-Sky Scale: 4.00

Mean SQM: 20.90


Basic astrometry details

Astrometry.net job: 3866896

RA center: 18h 3' 19"

DEC center: -22° 46' 15"

Pixel scale: 0.845 arcsec/pixel

Orientation: 180.055 degrees

Field radius: 0.669 degrees


Resolution: 4560x3423

Locations: Caswell Canyon, Anderson, North Carolina, United States

Data source: Backyard

Description

The Trifid is one of my favorite objects - I really love the red/blue contrasting colors.
It's pretty low in my sky and I had to catch it for the couple of hours it's visible between trees.
I really need to tweak my horizon files - the first 30 minutes were shot with the Newt pointing half above the observatory roof line, half below!

Acquisition spanned 8/9 to 9/15 over 11 nights. Funny, doesn't seem like we had that many decent nights over that period.

Stacked in APP, which did a nice job of blending my rotated light frames (camera came loose and spun around to a new position one night!). Also removed gradients and stacked HaRGB with APP. I like APP's newer channel combination feature - the presets and sliders make it quite easy to play with combinations. I ended up just adding the Ha to the R channel to boost the main nebula.

Did remaining post-processing in PI. PCC, MLT NR, Decon for the L frame, Arcsinh and masked stretch, LRGB Combination to add the L. Curves, HDRMT, Dark Structure Enhance script. Despite the low altitude for this target, didn't feel the need for any NR in the non-linear phase.

Then over to Photoshop for some star reduction on the big bright guys using Croman's StarShrink with a large radius to not shrink the smaller stars. Finished in 3D LUT Creator, a very cool tool (thanks Lloyd!) that lets you click on any color in the image and drag to affect the color intensity and hue for that color across the field. Selective Color on steroids with a large dollop of ease-of-use.

Had fun with this one, been gathering data and not processing for a few months. Good to see a result :) .

Comments

Author

Vassar1976
Rowland Archer
License: None (All rights reserved)
490
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Revisions

  • M20 - Trifid Nebula - M21 Open Cluster - TS ONTC Newtonian - LHaRGB, 



    
        

            Rowland Archer
    Original
  • Final
    M20 - Trifid Nebula - M21 Open Cluster - TS ONTC Newtonian - LHaRGB, 



    
        

            Rowland Archer
    B

B

Description: A bit lower brightness

Sky plot

Sky plot

Histogram

M20 - Trifid Nebula - M21 Open Cluster - TS ONTC Newtonian - LHaRGB, 



    
        

            Rowland Archer