IC434 & NGC 2024, Horsehead & Flame Nebulae, HαRRGB, 30 Dec 2016 (David Dearden)

Celestial hemisphere: Southern · Constellation: Orion (Ori) · Contains: 50 zet Ori · Alnitak · B33 · Horsehead nebula · IC 434 · NGC 2023 · NGC 2024 · Sh2-277 · The star Alnitak (ζOri)

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IC434 & NGC 2024, Horsehead & Flame Nebulae, HαRRGB, 30 Dec 2016

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IC434 & NGC 2024, Horsehead & Flame Nebulae, HαRRGB, 30 Dec 2016

I’m still struggling with color gradients, as is obvious in this HαRRGB image of the Horsehead and Flame Nebulae. The blue channel seemed especially problematic, and I got less data in B because the target was setting. This target is complicated by the brightness of Alnitak, which produces a nasty halo (which I did not try to eliminate) and some reflections (which I removed). I initially tried using just the Hα for luminance, but then decided to add in some of the R channel (which is quite bright) as well. We are beginning to build in a bad temperature inversion here, which means fog is becoming a factor too.

Date: 30 Dec 2016

Subject: IC 434 & NGC 2024, Horsehead and Flame Nebulae

Scope: AT8IN+High Point Scientific coma corrector

Filters: ZWO 31 mm RGB, ZWO 7nm Hα

Mount: EQ-6 (EQMOD)+PEC

Guiding: Orion TOAG +DSI Ic+PHD 2.6.2.4 (Win 10 ASCOM)

Camera: ASI1600MM-Cool, -20 °C, acquired Hα 1x1 RGB 2x2

Acquisition: Sequence Generator Pro 2.6.0.1

Exposure: 10x300 s R, 10x300 s G, 8x300 s B; 18x600 s Hα

Stacking: Neb 4.1.2, flats & darks, trans+rot align, Nebulosity 40-60%tile stack.

Processing: align and combine the unstretched R, G, B, attempting to align the histogram peaks. Stretch and sharpen the Hα data aggressively, the RGB less so in StarTools 1.4. Add the Hα as luminance to the RGB in Photoshop CC 2014 with Carboni’s Astronomy Tools, adjust curves on background to get colors about right; extensive use of healing brush to remove reflections; extensive levels and curves; Astroframe.

Original
Final
B

B

Description: Here's another try at handling the nasty color gradients, emphasizing the H-alpha that pervades this region. I have no idea why this file is so much larger than the previous one.

Uploaded: ...

ZWO ASI1600MM/QHY163M

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Status	Advanced success
Started	...
Astrometry.net job	1396753
PixInsight job	G0FO1K1E77S37UBNO26DHD4ND2HDTXZD
PixInsight queue size	n/a
PixInsight stage	n/a

RA (center)	05h41m05s.227
RA (top/left)	05h39m23s.478
RA (top/right)	05h39m26s.423
RA (bottom/right)	05h42m47s.197
RA (bottom/left)	05h42m44s.350

Dec (center)	-02°09′34″.45
Dec (top/left)	-01°37′21″.47
Dec (top/right)	-02°42′22″.42
Dec (bottom/right)	-02°41′48″.81
Dec (bottom/left)	-01°36′46″.24

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IC434 & NGC 2024, Horsehead & Flame Nebulae, HαRRGB, 30 Dec 2016

IC434 & NGC 2024, Horsehead & Flame Nebulae, HαRRGB, 30 Dec 2016

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IC434 & NGC 2024, Horsehead & Flame Nebulae, HαRRGB, 30 Dec 2016

IC434 & NGC 2024, Horsehead & Flame Nebulae, HαRRGB, 30 Dec 2016

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