Celestial hemisphere:  Southern  ·  Constellation: Orion (Ori)  ·  Contains:  B33  ·  Flame Nebula  ·  Horsehead nebula  ·  IC 434  ·  NGC 2023  ·  Orion B  ·  Sh2-277
IC 434 - The Horsehead Nebula, 


            Steve Ludwig
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IC 434 - The Horsehead Nebula

IC 434 - The Horsehead Nebula, 


            Steve Ludwig
Powered byPixInsight

IC 434 - The Horsehead Nebula

Acquisition details

Feb. 12, 2021
97×150(4h 2′ 30″)
4h 2′ 30″
Avg. Moon age:
0.71 days
Avg. Moon phase:

RA center: 05h41m07s.70

DEC center: -02°2733.9

Pixel scale: 1.198 arcsec/pixel

Orientation: -101.234 degrees

Field radius: 0.502 degrees

More info:Open 

Resolution: 2435x1785

File size: 909.0 KB

Data source: Backyard



- 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


- 97 lights x 150 s = 4 h 2.5 min

- no dark, flat, bias frames

- no filters

- ISO 400

- Bortle 4


- stacked in DSS

-> bilinear debayer method & median kappa sigma clipping

- unmodified TIF opened in PixInsight

-> STF stretch

-> crop

-> automatic background extraction (worked better than the dynamic version this time)

-> background neutralization

-> color calibration

-> histogram transformation

-> SCNR green to remove greenish noise

-> use of starnet++ module to separate stars and background


-> red channel extraction

-> range selection to create a smooth mask from the red channel image that contains the reddish hydrogen alpha regions

-> application of this mask to the original (color) background image

-> masked curves transformation to increase saturation and brightness of red hydrogen alpha regions without increasing color noise of the background

-> ACDNR to reduce background noise (using different mask for different background areas)

-> pixel math to recombine stars and background

-> resample 50%

-> final ACDNR with integrated lightness mask to reduce noise

-> another background neutralization to improve color balance a bit

-> histogram transformation

-> dynamic crop

-> saved as jpg



  • IC 434 - The Horsehead Nebula, 


            Steve Ludwig
  • Final
    IC 434 - The Horsehead Nebula, 


            Steve Ludwig


Description: In revision D, I applied much more aggressive ACDNR (applied to the background only) to reduce the overall noise level, which was very high in the first iteration. I think the result looks much better without appearing unnaturally smooth.

Uploaded: ...

Sky plot

Sky plot


IC 434 - The Horsehead Nebula, 


            Steve Ludwig