NGC 7023 - The Iris Nebula (Steve Ludwig)

NGC 7023 - The Iris Nebula

Equipment

- Main scope: Bresser Messier 10" Newton (254/1270)

- Main camera: Nikon D3300 (unmodified)

- Guide scope: Orion AC 50/162 Deluxe Mini

- Guide camera: ZWO ASI 290MC

- Mount: Skywatcher EQ6-R

- Explore Scientific HR coma corrector

Acquisition

- 78 lights x 300 s = 6 h 30 min

- no dark, flat, bias frames

- no filters

- ISO 800

- Bortle 4

Processing

- stacked in DSS

-> bilinear debayer method & median kappa sigma clipping

- unmodified TIF opened in PixInsight

-> STF stretch

-> dynamic crop

-> dynamic background extraction

-> background neutralization

-> color calibration

-> histogram transformation

-> Starnet++ to separate stars and background

Stars

-> SCNR green

-> invert

-> SCNR green to remove purple star edges (purple before inversion, now green)

-> invert

-> Curves transformation to increase saturation

Background

-> SCNR green

-> local histogram equalization to bring out detail in core

-> masked stretch to increase contrast of background dust

-> curves transformation with lightness mask to increase saturation of nebula core

-> curves transformation with lightness mask to decrease saturation of dust & background

-> massive ACDNR to reduce noise in background dust using the same mask

-> curves transformation without mask to balance overall brightness

-> pixel math to recombine stars and background

-> ACDNR to reduce noise

-> resample 50%

-> final curves transformation (fine tuning)

-> saved as jpg

Original
H
Final
I

H

Description: For this revision I separated the backround with the Pixinisght "Starnet++" plugin. Then I masked the bright core and stretched only the background. After using the "convolution" module on the resulting bright dust to reduce noise, I recombined the resulting background image with the stars.

Let me know in the comments which revision you prefer. The darker or brighter one?

Uploaded: ...

I

Description: For the latest revision I increased the color saturation a bit.

Uploaded: ...

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Status	Advanced success
Started	...
Astrometry.net job	3930169
PixInsight job	Y62J7NTHL3JDHJSJ80ZPMQF36JTG83DQ
PixInsight queue size	n/a
PixInsight stage	n/a

RA (center)	21h01m38s.21
RA (top/left)	21h07m01s.70
RA (top/right)	20h59m48s.69
RA (bottom/right)	20h56m14s.31
RA (bottom/left)	21h03m23s.21

Dec (center)	+68°10′16″.4
Dec (top/left)	+68°09′29″.7
Dec (top/right)	+68°38′37″.3
Dec (bottom/right)	+68°10′22″.9
Dec (bottom/left)	+67°41′50″.2

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