IC 4685 A Cloud with Character (Alex Woronow)

IC 4685 A Cloud with Character

IC 4685 A Cloud with Character

OTA:……………….TAO 150 (f/7.3)
Camera:………….FLI - ML16200 (1.13 arcsec/pixel)
Observatory:….Deep Sky West, Chile

EXPOSURES:

EXPOSURES:
…R: 16 x 600 sec.
…B: 11 x 600
…G: 18 x 600
…L: 19 x 600
…H: 11 x 1800
Total exposure   16 hours

Image Width: 1.3 deg
Processed by Alex Woronow (2022) using PixInsight, Topaz, 3DLut, SWT
Images captured 7/21
Rendered here at about 1/2 pixels/mm of full resolution

Usually portrayed as a fluffy, almost featureless cloud (as the name Baby Octopus Nebula probably implies), it is actually a happening place, as the jagged black cloud transecting it attests. (It is a dense, probably compacted, cloud resisting light penetration from the young stars embedded in the emission and reflection nebulae.)

I wondered whether the folksy names given to most of the nebulae influence the image processing done on them. Many nebulae have names suggesting softness in appearance or simpleness in shape, probably given when image processing was not nearly as capable as it is now or, maybe, given based on visual impressions in a modest amateur scope. Looking through images of this target on Astrobin, the vast-vast majority are, at best, lightly post-processed. Many appear to have ended the image processing just after combining, color balancing, and stretching the RGB stacks.

Why stop there when these clouds are known to be active, violent places of star birth and star death if not that the image then fits the object’s arcane name?

With the camera used here, and assuming that IC 4685 is about 400K ly away, the Nyquist resolution limit is about 8x10^13 km—hardly an extent too small to host considerable detail in a violent cloud such as the Baby Octopus Nebula!

BTW, at the time of capture, Mercury was not in fov!!!!

	Distinct awarded users	Total awarded images
Image of the day
Top picks
Top pick nominations

	Image of the day	Top pick	Top pick nominations	Total submitted
Deep sky
Solar system
Extremely wide field
Star trails
Northern lights
Noctilucent clouds
Landscape

	Image of the day	Top pick	Top pick nominations	Total submitted
Backyard
Traveller
Own remote observatory
Amateur hosting facility
Public amaeteur data
Professional, scientific grade data
Mix of multiple sources
Other
Unknown

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Status	Advanced success
Started	...
Astrometry.net job	5726818
PixInsight job	PVHPMRYV1VBX4MZB0V3WDLZBU90FQ9W8
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	18h09m18s.27
RA (top/left)	18h05m50s.80
RA (top/right)	18h11m37s.59
RA (bottom/right)	18h12m45s.13
RA (bottom/left)	18h07m00s.48

Dec (center)	-23°59′13″.2
Dec (top/left)	-24°20′48″.9
Dec (top/right)	-24°40′35″.1
Dec (bottom/right)	-23°37′20″.1
Dec (bottom/left)	-23°17′44″.2

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