Hemisphere:  Northern  ·  Contains:  14 Vul  ·  Dumbbell nebula  ·  M 27  ·  M27  ·  NGC 6853  ·  The star 14Vul
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M27, Dumbbell Nebula, HO+LRGB, 28 Jun-3 Jul 2019, 


            David Dearden
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M27, Dumbbell Nebula, HO+LRGB, 28 Jun-3 Jul 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: RC Astro GradientXTerminator  ·  DeepSkyStacker  ·  Silicon Fields StarTools 1.3  ·  Noel Carboni's Astro Tools for PhotoShop  ·  AstroPlanner  ·  PHD2 Guiding  ·  Sequence Generator Pro  ·  EQASCOM  ·  photoshop  ·  Enterprise Astronomy Annie's Astro Actions

Filters: ZWO Red 31 mm  ·  ZWO Luminance 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 28, 2019June 29, 2019July 2, 2019July 3, 2019

ZWO Blue 31 mm: 16x180" (gain: 139.00) -20C bin 1x1
ZWO Green 31 mm: 15x180" (gain: 139.00) -20C bin 1x1
ZWO H-alpha 7nm: 24x300" (gain: 139.00) -20C bin 1x1
ZWO Luminance 31 mm: 50x180" (gain: 139.00) -20C bin 1x1
ZWO OIII 31 mm 7 nm: 24x300" (gain: 139.00) -20C bin 1x1
ZWO Red 31 mm: 23x180" (gain: 139.00) -20C bin 1x1

Integration: 9.2 hours

Avg. Moon age: 20.26 days

Avg. Moon phase: 8.83%

Bortle Dark-Sky Scale: 5.00

Astrometry.net job: 2782687

RA center: 19h 59' 37"

DEC center: +22° 44' 39"

Pixel scale: 1.718 arcsec/pixel

Orientation: -176.934 degrees

Field radius: 0.699 degrees

Resolution: 2318x1790

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

Data source: Backyard


1227 LY

What a difference a little more data can make! Not satisfied with the LRGB image I posted a few days ago, I decided to get Hα and OIII data for the Dumbbell Nebula. This target really pops with these filters; I think this is the strongest OIII target I have seen. Processing this image was more difficult than usual and I have struggled with it. Using my normal approach the colors came out very weak and unconvincing. So I tried a lot of different ways of processing and finally settled on separately doing the Hα and OIII. I backed off the temptation to fully stretch to bring out the faint outer portions. This allowed some of the structure of the interior of the nebula to show up without becoming fully saturated. I played with bicolor combination of Hα and OIII, and finally tried layering the LRGB on top as a color layer at 50% opacity, which seemed to preserve the detail and the faint parts of the nebula but gave colors I liked a little better. This also de-emphasized the star field while preserving its color. There’s still more noise than I like, but I’ve spent enough on this now. It’s interesting to see the different shells of gas ejected from the star that show up in this nebula. Now I think I have a better M27 than I got from my OSC camera; it looks like a delicate cosmic butterfly.

Date: 28 June-3 July 2019
Subject: M27, Dumbbell Nebula
Scope: AT8IN+High Point Scientific Coma Corrector
Filters: ZWO 31 mm diameter unmounted 7 nm L, R, G, B, 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: 50x180 L, 7x180 R, 15x180 G, 16x180 B, 24x300 Hα, 24x300 OIII
Stacking: Deep Sky Stacker 4.2.0 beta 5 (64-bit) dark+flat+bias, κ-σ stacking with κ = 1.5.
Processing: StarTools 1.4.352: Cropped, wiped, developed (holding back a bit), HDR equalized, deconvoluted, and untrack denoised the Hα and OIII data. Combined using Annie’s Astro Actions HO Bicolor process. Did adjustments to saturation and a bit of curves and levels. GradientXterminator (medium, low). Several rounds of curves+levels. Added LRGB from 29 June 2019 as a color layer at 50% opacity on top of the HO. AstroFrame.



David Dearden
License: None (All rights reserved)

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M27, Dumbbell Nebula, HO+LRGB, 28 Jun-3 Jul 2019, 


            David Dearden