Celestial hemisphere:  Southern  ·  Constellation: Sagittarius (Sgr)  ·  Contains:  B85  ·  M 20  ·  M 21  ·  NGC 6514  ·  NGC 6531  ·  Sh2-30  ·  Trifid nebula
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M20, Trifid Nebula, HO Bicolor, 4-13 May 2017, David Dearden
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M20, Trifid Nebula, HO Bicolor, 4-13 May 2017

Getting plate-solving status, please wait...
M20, Trifid Nebula, HO Bicolor, 4-13 May 2017, David Dearden
Powered byPixInsight

M20, Trifid Nebula, HO Bicolor, 4-13 May 2017

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Acquisition details

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Description

This was sort of throw-away data, but I processed it anyway. I had intended this to be a deep image of the Trifid Nebula, but due to bad weather and the timing of trips, never got all the data I wanted. So I finally decided to see what I could do with what I got. The take-home lesson from this image is something I have recently read but is proven to me here: you can’t take OIII subframes at full moon. The luminance and Hα were OK, but the OIII subs were horrible. I checked what the moon phase was, and sure enough, it was nearly full when I did the OIII.

Date: 4-13 May 2017

Subject: M20, Trifid Nebula.

Scope: AT8IN + High Point Scientific coma corrector

Filters: ZWO 31 mm diameter unmounted L, Hα, OIII

Mount: EQ-6 (EQMOD)+PEC

Guiding: Orion Thin Off-axis Guider + DSI +PHD 2.6.3 (Win 10 ASCOM)

Camera: ASI1600MM-Cool, -20 °C, Gain 139 Offset 21

Acquisition: Sequence Generator Pro 2.6.0.23?

Exposure: 34x300 L, 20x600 Hα, 17x600 OIII

Stacking: Neb 4.1.6, flats & darks, trans+rot align, Nebulosity 1.5σ stack and align.

Processing: StarTools 1.4.328: Aggressively stretched and deconvoluted L and Hα; made due with poor OIII data in StarTools. HO combined with Annie’s Astro Actions. Had to do a lot of layer-masked touchup with the Photoshop clone stamp to get rid of flaws from bad flats. AstroFrame.

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M20, Trifid Nebula, HO Bicolor, 4-13 May 2017, David Dearden