Hemisphere:  Northern  ·  Contains:  Sh2-170
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Sh2-170, Small Rosette Nebula, HαRGB, 27-28 Aug 2019, 


            David Dearden
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Sh2-170, Small Rosette Nebula, HαRGB, 27-28 Aug 2019

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  ·  Silicon Fields StarTools 1.3  ·  AstroPlanner  ·  PHD2 Guiding  ·  Sequence Generator Pro  ·  EQASCOM  ·  photoshop

Filters: ZWO Red 31 mm  ·  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:Aug. 27, 2019Aug. 28, 2019

ZWO Blue 31 mm: 23x180" (gain: 139.00) -20C bin 1x1
ZWO Green 31 mm: 20x180" (gain: 139.00) -20C bin 1x1
ZWO H-alpha 7nm: 34x300" (gain: 139.00) -20C bin 1x1
ZWO Red 31 mm: 20x180" (gain: 139.00) -20C bin 1x1

Integration: 6.0 hours

Avg. Moon age: 26.72 days

Avg. Moon phase: 8.98%

Bortle Dark-Sky Scale: 5.00

Astrometry.net job: 3007398

RA center: 0h 1' 31"

DEC center: +64° 36' 0"

Pixel scale: 1.719 arcsec/pixel

Orientation: 3.727 degrees

Field radius: 0.692 degrees

Resolution: 2298x1770

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

Data source: Backyard


8100 ± 1000 LY

I thought I could do better with this object than in the past, so gave it an attempt. It shows up reasonably well in Hα but with shorter exposures using R, G, and B the nebulosity hardly shows at all. Neither did I get anything in SII. These kinds of objects usually don’t show much in OIII so I was lazy and didn’t try that, although I see online that its center does emit a little in OIII.

Date: 27, 28 Aug 2019
Subject: Sh2-170, Small Rosette Nebula
Scope: AT8IN+High Point Scientific Coma Corrector
Filters: ZWO 31 mm diameter unmounted 7 nm Hα, OIII
Mount: EQ-6 (EQMOD 2.000j)+PEC
Guiding: Orion Thin Off-axis Guider + ASI120MM-mini +PHD 2.6.6 (Win 10 ASCOM)
Camera: ASI1600MM-Cool, -20 °C, Gain 139 Offset 21
Acquisition: Sequence Generator Pro
Exposure: 34x300 Hα, 20x180 R, 20x180 G, 23x180 B
Stacking: Deep Sky Stacker 4.2.2 (64-bit) dark+flat+bias, κ-σ stacking with κ = 1.5.
Processing: StarTools 1.4.352: Software binned 2x2, cropped, wiped, developed, HDR optimized, deconvoluted, and untrack denoised the Hα. Combined R, G, & B in StarTools, binned 2x2, cropped, developed, HDR optimized, boosted saturation and untracked denoised. Combined Hα and R (50% each) in Photoshop and used the combination as the R layer. Used Hα as luminance. Curves & Levels, saturation boost, capped by some layer-masked saturation boost for just the nebula. AstroFrame.



David Dearden
License: None (All rights reserved)

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Sh2-170, Small Rosette Nebula, HαRGB, 27-28 Aug 2019, 


            David Dearden