NGC 2237 - a spanner in the works (Tom Gray)

NGC 2237 - a spanner in the works

Revision title: Colour calibration, RGB stars and Astrosharp

Lying 5000 LY away in Monoceros, this large emission nebula is ~130 LY in diameter and surrounds the bright star cluster NGC 2244, which has condensed from the surrounding nebulosity and now energises it with powerful UV irradiation, creating extraordinary structures in the dust and molecular gas clouds - can you see the spanner? This version taken with my OSC and a dual band L-eNhance filter shows a strong hydrogen rim, surrounding lighter OIII.

Imaged over two nights, there is just about enough integration to show off the detail. 5 minute exposures on the Star Adventurer tracker are possible with good alignment, balance and guiding. Calibrated and stacked, this image is post-processed using simple levels and curves in Nebulosity.

[Postscript - I’ve applied deconvolution to the final image in Startools for a much sharper image, reducing the optical and atmospheric blurring.]

Original
B
D
E
Final
F

B

Title: Deconvolution applied in Startools for a higher spec spanner

Uploaded: ...

D

Title: Processed in SiRIL 1.06

Description: Pre-processed in Nebulosity 4, processed in SiRIL - photometric colour calibration, SNCR, deconvolution and finished in Nebulosity 4 - star tightening and GreyCstoration. I think this smoother image has better colour and depth.

Uploaded: ...

E

Title: The Arty version

Description: Messing with SiRIL pixel math and composite images - SHO (false) colour scheme.

Uploaded: ...

F

Title: Colour calibration, RGB stars and Astrosharp

Description: My final version - more sympathetic than my last, IMHO. Using basic colour calibration in Siril for background extraction, draws out the HOO colours from my L-eNhance filter. GHS transformation with saturation. Astrosharp applied to the starless image. Starnet removal and photometric calibration of starfield for 'true' RGB stars, recomposition and final noise reduction. I hope you like it.

Uploaded: ...

Altair Astro 183 M/C Hypercams
UK Astro-Imaging
Optolong L-eNhance filter

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Status	Advanced success
Started	...
Astrometry.net job	8223277
PixInsight job	1NTDWS9OBDNKKE6RC52AQ4WDAN83ESAI
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	06h31m51s.63
RA (top/left)	06h33m39s.53
RA (top/right)	06h33m09s.30
RA (bottom/right)	06h30m03s.54
RA (bottom/left)	06h30m34s.50

Dec (center)	+04°59′29″.4
Dec (top/left)	+04°25′10″.4
Dec (top/right)	+05°38′34″.7
Dec (bottom/right)	+05°33′47″.5
Dec (bottom/left)	+04°20′27″.4

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