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Contains:  NGC 1491, NGC1491, Sh2-206
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Sh2-206, SHO Hubble Palette with RGB Stars, 7-9 Nov 2018, 


            David Dearden
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Sh2-206, SHO Hubble Palette with RGB Stars, 7-9 Nov 2018

Technical card

Dates:Nov. 7, 2018Nov. 8, 2018Nov. 9, 2018

ZWO Blue 31 mm: 30x180" (gain: 139.00) -20C bin 1x1
ZWO Green 31 mm: 30x180" (gain: 139.00) -20C bin 1x1
ZWO H-alpha 7nm: 36x300" (gain: 139.00) -20C bin 1x1
ZWO OIII 31 mm 7 nm: 36x300" (gain: 139.00) -20C bin 1x1
ZWO Red 31 mm: 30x180" (gain: 139.00) -20C bin 1x1
ZWO SII 7nm: 24x300" (gain: 139.00) -20C bin 1x1

Integration: 12.5 hours

Avg. Moon age: 10.67 days

Avg. Moon phase: 1.50%

Bortle Dark-Sky Scale: 5.00 job: 2368869

RA center: 4h 4' 9"

DEC center: +51° 14' 18"

Pixel scale: 1.718 arcsec/pixel

Orientation: -85.973 degrees

Field radius: 0.699 degrees

Resolution: 2318x1790

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

Data source: Backyard


This not-as-frequently-imaged object was in the right place in my sky for a new try. Even though the background is stretched hard enough that the noise is showing more than I like, I thought this was so much better than my attempt 4 years ago that I thought I’d go ahead with it. Nearly all the nebulosity shows up in Hα, but the central region of the nebula lights up with all the filters and is considerably brighter than the periphery. I’ve gone back and forth about whether this is better to show in SHO or HSO, and ultimately decided I like SHO better because the structure in the nebula shows up better to my eye this way even though the colors are “more false” than in HSO (which is really just as false).

Date: 7-9 Nov 2018
Subject: Sh2-206
Scope: AT8IN+High Point Scientific Coma Corrector
Filters: ZWO 31 mm diameter unmounted 7 nm Hα, SII, OIII, R, G, B
Mount: EQ-6 (EQMOD 2.000j)+PEC
Guiding: Orion Thin Off-axis Guider + DSI IIc +PHD 2.6.5 (Win 10 ASCOM)
Camera: ASI1600MM-Cool, -20 °C, Gain 139 Offset 21
Acquisition: Sequence Generator Pro
Exposure: 36x300 Hα, 24x300 SII, 36x300 OIII, 30x180 R, 30x180 G, & 30x180 B
Stacking: Deep Sky Stacker 4.1.1 (64-bit) dark+flat (no bias), κ-σ stacking with κ = 1.5.
Processing: StarTools 1.4.332: 2x2 Software binned all the data, which were collected 1x1. Cropped and wiped Hα, then stretched, applied HDR (optimize), masked out the “fat” stars, aggressively deconvoluted, then did untrack denoise. Followed essentially the same procedure for SII and OIII. Combined SHO in Photoshop using Annie’s Astro Actions, and played with the color balance to get it roughly how I thought it should look. I ended up with several different combinations I liked. Combined R, G, & B in StarTools. Cropped with vignette wipe, developed, HDR optimized, and applied default color module settings. Deconvoluted and denoised. Added RGB stars by extracting them from the RGB image and use screen combine to put them on top of the SHO.



David Dearden
License: None (All rights reserved)


  • Final
    Sh2-206, SHO Hubble Palette with RGB Stars, 7-9 Nov 2018, 


            David Dearden
  • Sh2-206, SHO Hubble Palette with RGB Stars, 7-9 Nov 2018, 


            David Dearden


Description: SHO version of the same data

Sky plot

Sky plot


Sh2-206, SHO Hubble Palette with RGB Stars, 7-9 Nov 2018, 


            David Dearden