IC 342, The Hidden Galaxy (Bill Dirks)

IC 342, The Hidden Galaxy

A large-apparent-size face-on spiral galaxy, but with low surface brightness and obscured by Milky Way dust. Spectacular spiral structure fills my entire sensor.

Struggled with very poor seeing in the beginning, and this turned into quite a project. Exposures acquired over 9 nights, including the night of the full moon. To block moonlight when it was strong I made a 'moon shade' out of a sheet of black foam, and clipped it to the dew shield. Eventually accumulated over 49 hours of exposures, but this image only uses 34 hours of it.

The acquisition details above show all raw frames captured. This final image uses:
L - 240 frames (of 371) x 300s @ Gain 100 @ -20C = 20h 00m
R - 57 frames (of 70) x 300s @ Gain 200 @ -20C = 4h 45m
G - 57 frames (of 70) x 300s @ Gain 200 @ -20C = 4h 45m
B - 59 frames (of 82) x 300s @ Gain 200 @ -20C = 4h 55m
34h 25m total exposure time

The galaxy after color calibration (PixInsight SPCC) has a strong orange/brown cast due to Milky Way dust. I have done an additional manual (and subjective!) white balance to make the spiral arms roughly neutral. So I hope this has recovered the true colors of the galaxy.

Original
Final
B

B

Description: Using original data, but started over from scratch.

Restacked in PixInsight WBPP tool with twice as many hours of L filter data, and also a little more R,G,B data; 34.5h total (versus 23h in DeepSkyStacker for first revision).

Compared to first revision:
Slightly wider crop. Not so bright, washed out, especially central area. Better definition of dust lanes, especially the tiger stripes in the central area. Brought out blues better; a challenge on this object! Preserved correct detail and color in core (clear blue color). Much less false color in faint areas. Slightly better definition of small structures in faint areas. Overall less noisy.

Uploaded: ...

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Status	Advanced success
Started	...
Astrometry.net job	9120732
PixInsight job	O034O6N083ZNBPODYQY6D2VD9TRQCOYO
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	03h46m48s.451
RA (top/left)	03h48m49s.826
RA (top/right)	03h44m42s.532
RA (bottom/right)	03h44m48s.971
RA (bottom/left)	03h48m52s.362

Dec (center)	+68°05′39″.59
Dec (top/left)	+68°17′07″.42
Dec (top/right)	+68°16′41″.93
Dec (bottom/right)	+67°54′06″.70
Dec (bottom/left)	+67°54′32″.10

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