Hemisphere:  Northern  ·  Contains:  Sh2-112
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Sh2-112, SHO (Hubble Palette) with RGB stars, 26-27 Jun 2018 and 22-24 June 2020, 



    
        

            David Dearden
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Sh2-112, SHO (Hubble Palette) with RGB stars, 26-27 Jun 2018 and 22-24 June 2020

Imaging telescopes or lenses: Astro-Tech AT8IN

Imaging cameras: ZWO ASI1600MM-Cool

Mounts: Skywatcher NEQ-6 Pro Synscan

Guiding telescopes or lenses: Astro-Tech AT8IN

Guiding cameras: ZWO AS120MM-Mini

Focal reducers: High Point Scientific Coma Corrector Photo & Visual For Netwonian Telescopes 2"

Software: DeepSkyStacker  ·  Noel Carboni's Astro Tools for PhotoShop  ·  StarTools  ·  AstroPlanner  ·  PHD2 Guiding  ·  Sequence Generator Pro  ·  Cartes du Ciel  ·  EQASCOM  ·  photoshop

Filters: ZWO Red 31 mm  ·  ZWO OIII 31 mm 7 nm  ·  ZWO Green 31 mm  ·  ZWO H-alpha 7nm  ·  ZWO Blue 31 mm

Accessory: Orion Thin Off Axis Guider (TOAG)  ·  Robert Brown's Arduino ASCOM Focuser Pro DIY  ·  ZWO EFW filter wheel


Dates:June 26, 2018June 22, 2020June 23, 2020June 24, 2020

Frames:
ZWO Blue 31 mm: 15x120" ISO139 (gain: -20.00) bin 1x1
ZWO Green 31 mm: 15x120" (gain: 139.00) -20C bin 1x1
ZWO H-alpha 7nm: 81x300" (gain: 139.00) -20C bin 1x1
ZWO OIII 31 mm 7 nm: 30x300" (gain: 139.00) -20C bin 1x1
ZWO Red 31 mm: 15x120" (gain: 139.00) -20C bin 1x1
ZWO SII 7nm: 30x300" (gain: 139.00) -20C bin 1x1

Integration: 13.2 hours

Avg. Moon age: 4.99 days

Avg. Moon phase: 29.09%

Bortle Dark-Sky Scale: 5.00


Astrometry.net job: 3637719

RA center: 20h 34' 46"

DEC center: +45° 29' 25"

Pixel scale: 1.720 arcsec/pixel

Orientation: -92.654 degrees

Field radius: 0.656 degrees


Resolution: 2188x1660

Locations: Mapleton Lateral Observatory, Mapleton, Utah, United States

Data source: Backyard

Description

5500 ± 500 ly

I had some fun with this target. Looking for something appropriately placed in the sky and about the right size for my imaging train, I found Sh2-112 in my list of possibilities. When I went to save the imaging sequence in Sequence Generator Pro, I found I already had a sequence by the same name, which led me to look closer. I found I had already taken a goodly number of Hα subframes in 2018, but never finished collecting or stacking the data, and then forgot about it. So I took more Hα, added OIII and SII, and took some RGB as well. Playing with the processing was also fun. I was trying some different ways to run the stacking in Deep Sky Stacker and accidentally managed to stack all the Hα, OIII, and SII data together. Rather than throwing it away, I thought I might try using it as a luminance layer. I also did a straight up StarTools SHO combine, and found that using my combined stack as a luminance layer with that seemed to improve the image. Next I wanted to add in RGB stars, so I took a short set of RGB exposures (15 2-minute exposures with each filter) and did the RGB stack in StarTools. The default color module settings gave star colors I liked. I put this layer on top of the SHO with “all filter” luminance in Photoshop and used “Lighter color” to get RGB stars with SHO nebulosity. This did make my stars bigger, somewhat overwhelming the nebula, so I hit on the idea of using the original SHO layer again on top as a luminosity layer. This produced a result I liked, making the stars smaller without affecting the nebula. Finally, I usually play with turning the layers on and off to see what using them does, and was happy to see that if I turned off the bottom SHO layer—which I almost never try (leaving a “lighter color” RGB layer with the SHO luminance on top—I got a view of the nebula with the contrast of the SHO but the RGB colors. Liking this, I kept it too. I think there’s probably a little more structure-revealing contrast in the Hubble palette version, but it’s a close call (and I’d love to hear others’ opinions). I saw a pretty wide range of distance estimates for Sh2-112, so I went with a rough average.

Date: 26-27 Jun 2018, 22-24 Jun 2020
Subject: Sh2-112
Scope: AT8IN+High Point Scientific Coma Corrector
Filters: ZWO 31 mm diameter unmounted 7 nm bandpass Hα, OIII, and SII; R, G, B
Mount: EQ-6 (EQMOD 2.000j)+PEC
Guiding: Orion Thin Off-axis Guider + ASI120MM-mini +PHD 2.6.8 (Win 10 ASCOM)
Camera: ASI1600MM-Cool, -20 °C, Gain 139 Offset 21
Acquisition: Sequence Generator Pro 3.1.0.479
Exposure: 71x300 Hα, 30x300 OIII, 30x300 SII, 15x120 R, 15x120 G, 15x120 B
Stacking: Deep Sky Stacker 4.2.3 (64-bit) dark+flat+bias, κ-σ stacking with κ = 1.5
Processing: StarTools 1.6.394RC: Composed Hα, OIII, and SII in StarTools accounting for exposures to create a synthetic luminance. Software binned 2x2, cropped, and vignette wiped. Developed at 94%, HDR (reveal all), deconvoluted and untracked denoised (grain equalization). Composed R, G, & B accounting for total integration times in creating a combined synthetic luminance. Software binned 2x2, cropped, vignette wiped, developed (94%), HDR (reveal all), deconvoluted slightly, ran the color module with default settings, and untrack denoised (grain elimination). In Photoshop, played with things as described above. AstroFrame.

Comments

Author

dvdearden
David Dearden
License: None (All rights reserved)
1281
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Revisions

  • Final
    Sh2-112, SHO (Hubble Palette) with RGB stars, 26-27 Jun 2018 and 22-24 June 2020, 



    
        

            David Dearden
    Original
  • Sh2-112, SHO (Hubble Palette) with RGB stars, 26-27 Jun 2018 and 22-24 June 2020, 



    
        

            David Dearden
    B

B

Description: The more "natural" color version as described.

Sky plot

Sky plot

Histogram

Sh2-112, SHO (Hubble Palette) with RGB stars, 26-27 Jun 2018 and 22-24 June 2020, 



    
        

            David Dearden