Hemisphere:  Northern  ·  Constellation: Triangulum (Tri)  ·  Contains:  M 33  ·  NGC 598  ·  Triangulum Galaxy  ·  Triangulum Pinwheel
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The Triangulum Galaxy (M33) in LHαRGBOiii, 



    
        

            Brent Newton
The Triangulum Galaxy (M33) in LHαRGBOiii
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The Triangulum Galaxy (M33) in LHαRGBOiii

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The Triangulum Galaxy (M33) in LHαRGBOiii, 



    
        

            Brent Newton
The Triangulum Galaxy (M33) in LHαRGBOiii
Powered byPixInsight

The Triangulum Galaxy (M33) in LHαRGBOiii

Technical card

Imaging telescopes or lenses: William Optics Star 71 APO Refractor

Imaging cameras: ZWO ASI 1600MM Cooled Pro

Mounts: Celestron CGEM II

Guiding telescopes or lenses: Orion 50mm GuideScope

Guiding cameras: ZWO ASI 224 MC

Software: PHD2  ·  Pixinsight  ·  Astroplace Astrophotography tools APT

Filters: ZWO Lum 36mm  ·  ZWO 36mm 7nm Ha  ·  ZWO 36mm 7nm OIII  ·  ZWO 36mm Green Filter  ·  ZWO 36mm Red Filter  ·  ZWO 36mm Blue Filter

Accessory: AstroZap Dew Heater


Dates:Oct. 1, 2020Oct. 11, 2020Oct. 12, 2020Oct. 13, 2020Nov. 1, 2020Nov. 2, 2020Nov. 7, 2020Nov. 10, 2020Nov. 11, 2020Nov. 12, 2020Nov. 15, 2020

Frames:
ZWO 36mm 7nm OIII: 207x300" (17h 15') (gain: 139.00) -20C bin 1x1
ZWO Lum 36mm: 308x180" (15h 24') (gain: 76.00) -20C bin 1x1
ZWO 36mm 7nm Ha: 227x300" (18h 55') (gain: 139.00) -10C bin 1x1
ZWO 36mm Blue Filter: 69x300" (5h 45') (gain: 76.00) -10C bin 1x1
ZWO 36mm Green Filter: 69x300" (5h 45') (gain: 76.00) -10C bin 1x1
ZWO 36mm Red Filter: 69x300" (5h 45') (gain: 76.00) -10C bin 1x1

Integration: 68h 49'

Darks: ~100

Flats: ~30

Avg. Moon age: 19.78 days

Avg. Moon phase: 44.67%

Bortle Dark-Sky Scale: 4.00


Basic astrometry details

Astrometry.net job: 4145539

RA center: 1h 33' 50"

DEC center: +30° 39' 18"

Pixel scale: 1.139 arcsec/pixel

Orientation: 40.994 degrees

Field radius: 1.633 degrees


Resolution: 8400x6000

Locations: General Area, Wichita, Kansas, United States

Data source: Backyard

Description

Shot from my new Bortle 4 place just outside Wichita. Had a lot of fun with this one, mostly because I found the addition of Oiii to be useful in balancing the galaxy color against the red Hα and because it also provided more detail in some of the emission regions. The only downside is that the effect of combining the O as well as the H meant there was a lot of overlap, and this caused much of the emission regions to turn overall white as a result. To get around this I first isolated the Hα from the continuum per the LVT page, then isolated the Oiii image using the Hα image as a stand in for "broadband" to ensure the overlap between the two was minimized. The only downside of this is that the halos from the Oiii around the brighter stars still made it through, despite my efforts at clone stamping.

Once everything was combined (LRGB onward) I found the narrowband provided much more than just the brighter discreet emission nebula, but also a lot of wider and more diffuse oceans of Hα. At first I thought this may be large scale color noise but when comparing it to the narrowband images it seemed to match up.

Calib/Housekeeping:
- BPP, CC, SS Weighing, SA, Local Norm, Image Int, Drizzle 2x for the Hα, Oiii, Lum
- Common Crop
- DBE passes
- LFit R, B, to G
- RGB Combine

Lum, Hα, Oiii Processing:
- Decon for each using Dynamic PSF, StarMask (2 passes for Lum)
- TGVD, MMT (Rista)
- Isolated and blended Hα into Lum
- Isolated Oiii from Hα, then blended into Lum

- Masked Stretch combined Lum
- Blended the brighter stars from a regular Histogram Stretched copy over it
- ACDNR (Rista)

RGB Processing:
- Photometric CC
- Blending of Hα and Oiii into R/GB using LightVortexTutorials method (after running StarNet and CloneStamping out the Oiii halos)
- Magenta Star Script, HSV Repair
- TGVD, MMT (Rista) for both CNR, LNR
- SCNR for G reduction
- ArcSinH + Masked Stretch
- ACDNR (Rista)
- LRGB Combination

LRGB Processing:
- MorphologicalTransformation
- Final NR via ACDNR
- C* increases and a*b adjustments using various galaxy, narrowband, and star masks
- Ran DarkStructureEnh to isolate spiral arm mask, then applied and used Curves to increase contrast of spiral structure
- Couple passes of Unsharp Mask for NB detail and subtle increase of small stars inside galaxy
- Various Curves/Hist alterations for contrast

Comments

Revisions

  • Final
    The Triangulum Galaxy (M33) in LHαRGBOiii, 



    
        

            Brent Newton
    Original
    The Triangulum Galaxy (M33) in LHαRGBOiii, 



    
        

            Brent Newton
    B

B

Description: Reprocess using a combined Hα/Oiii as Luminance for the broadband RGB data, skipping broadband Luminance

Uploaded: ...

Sky plot

Sky plot

Histogram

The Triangulum Galaxy (M33) in LHαRGBOiii, 



    
        

            Brent Newton