Contains: M 43, NGC 1982, NGC 1977, NGC 1980, M 42, Great Nebula in Orion, NGC 1976, NGC 1975, NGC 1973, The star 45Ori, The star ιOri, The star θ2Ori, The star θ1Ori, The star 42Ori
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The sword of Orion

Technical card

Resolution: 1988x1344

Dates: Nov. 30, 2016

10x1" ISO1600
10x15" ISO1600
10x4" ISO1600
44x60" ISO1600

Integration: 0.8 hours

Flats: ~21

Bias: ~72

Avg. Moon age: 0.88 days

Avg. Moon phase: 0.88%

Bortle Dark-Sky Scale: 7.00

Temperature: -4.00 job: 1436019

RA center: 83.787 degrees

DEC center: -5.251 degrees

Pixel scale: 2.665 arcsec/pixel

Orientation: 103.847 degrees

Field radius: 0.888 degrees


The original images (rev. A and B) show M42 in heavy light pollution, taken from the city center on Feb 24, 2016.

I revisited this popular target after 9 months, this time from my dark site (red zone, Bortle 7) and doubled the integration time. Separate exposures were taken for the core, stacked in DSS and layered in StarTools.

Original description:
"I wonder whether filters will increase the quality of my subs, since I cannot expose for longer than 30 sec at ISO-1600 without overexposing... Also, I need to find out what's causing the black circles in the image. Please post any ideas in the comments! Edit B: included 20 Flats and re-stretched the image more conservatively, looks better now!"

Original technical card:
40x30" ISO1600
20 Flats (added in revision B)
72 Bias (added in revision B)
Bortle Dark-Sky Scale: 9.00
Orion ShorTube 80, EQ5 Pro and 450D



Victor Van Puyenb...



New stack from better location


Reprocessed 60sec exposures in PixInsight


Reprocessed as HDR

Sky plot

Sky plot


The sword of Orion, Victor Van Puyenbroeck

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