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Contains:  M 43, NGC 1982, M 42, Great Nebula in Orion, NGC 1976, The star θ2Ori, The star θ1Ori
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M42, Great Nebula in Orion, LHαGB, 15 Mar 2019, 


            David Dearden
M42, Great Nebula in Orion, LHαGB, 15 Mar 2019

M42, Great Nebula in Orion, LHαGB, 15 Mar 2019

Technical card

Resolution: 2318x1790

Dates:March 15, 2019

ZWO Blue 31 mm: 20x120" (gain: 139.00) -20C bin 1x1
ZWO Green 31 mm: 12x120" (gain: 139.00) -20C bin 1x1
ZWO H-alpha 7nm: 15x180" (gain: 139.00) -20C bin 1x1
ZWO Luminance 31 mm: 20x10" (gain: 139.00) -20C bin 1x1
ZWO Luminance 31 mm: 20x120" (gain: 139.00) -20C bin 1x1

Integration: 2.5 hours

Avg. Moon age: 8.50 days

Avg. Moon phase: 61.76%

Bortle Dark-Sky Scale: 5.00 job: 2592502

RA center: 83.741 degrees

DEC center: -5.475 degrees

Pixel scale: 1.718 arcsec/pixel

Orientation: 177.413 degrees

Field radius: 0.699 degrees

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

Data source: Backyard


1344 ± 20 LY

Here’s an attempt at LHαGB imaging of the Orion Nebula with far too little data. I’ve been wanting to get to it with my ASI camera but the weather has not cooperated and at this point I’ll need to wait until next year for more. The quintessential winter object posted on the first day of spring. I had horrible vignetting issues with this image. It’s not a particularly deep image, and I obviously struggled with the dynamic range around the Trapezium, but I like how the colors turned out and the detail is better than in any of my previous attempts so I guess I’ll keep it. I used Hα in place of red.

Date: 15 Mar 2019
Subject: M42, Great Nebula in Orion
Scope: AT8IN+High Point Scientific Coma Corrector
Filters: ZWO 31 mm diameter unmounted 7 nm L, Hα, G, B
Mount: EQ-6 (EQMOD 2.000j)+PEC
Guiding: Orion Thin Off-axis Guider + DSI IIc +PHD 2.6.5dev6 (Win 10 ASCOM)
Camera: ASI1600MM-Cool, -20 °C, Gain 139 Offset 21
Acquisition: Sequence Generator Pro
Exposure: 18x180 Hα, 15x120 L, 20x10 L, 12x120 G, & 20x120 B
Stacking: Deep Sky Stacker 4.1.1 (64-bit) dark+flat (no bias), κ-σ stacking with κ = 1.5.
Processing: StarTools 1.4.341: Software binned everything 2x2 with a 25 pixel border crop. Gradient wiped Hα and L. Stretched and HDR optimized. Deconvoluted and untrack denoised. Separately processed G & B and stretched about the same amount but did no deconvolution. Used Photoshop Annie’s Astro Actions for RGB combine, using Hα for R. Blended 10 s L with 120 s L (with a Gaussian blurred layer mask) to retain some detail in the core. Used a combination of the combined L and Hα as overall luminance, again employing layer masks to remove some bad vignetting errors (I need to work on my scope!). Boosted saturation to taste. AstroFrame.



David Dearden
License: None (All rights reserved)

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M42, Great Nebula in Orion, LHαGB, 15 Mar 2019, 


            David Dearden