NGC 6888 in RGB and HO Extracted Lines (based on a Nyquist Reconstruction) (Alex Woronow)

NGC 6888 in RGB and HO Extracted Lines (based on a Nyquist Reconstruction)

NGC 6888 in RGB and HO Extracted Lines (based on a Nyquist Reconstruction)

OTA: Star-Fire 175 (f/8)
Camera: FLI - PL16070AE
Observatory: Deep Sky West, NM

EXPOSURES:
R: 22 x 300 seconds
B: 19 x 300
G: 22 x 300
H: 19 x 1800
O: 17 x 1800
Total exposure 22.7 hours
Processed by Alex Woronow (2022) using PixInsight, Topaz, et. al

The RGB image consist includes true-color mapped Ha and OIII emission lines with the L channel taken from the HO image (Image B).
At the bottom of image B is another small bubble nebula. It is difficult to see in RGB, but in HO, it’s quite obvious. Does anyone know the ID for this object? I have gone through a few catalogs with no success.

As for image processing, I tried something different on these images: starting from a “Nyquist Reconstruction” (NR). My background on this NR thingy is extremely limited. Anyone with more information (e.g., that no one should ever do it because…. )? I’d like to learn more on this topic. But, having processed the image once without this NR and then with NR, it seems to suppress artifacts that, I would guess, came from aliasing.

The image was processed after removing the stars. The stars that were replaced in the RGBHO image are those from the HO image (C), so there are some imperfect matches with the RGBHO nebula, but at least the stars do not now hide all the interesting detail as I find them apt to do.

Along the trail of processing, some of the intermediate images clearly showed that the red components of the nebula are entirely wrapped in a blue haze (Image C). That fact does not show clearly in the final image, however, but it does adversely affect the ability to reveal structural details.

Anyway, hope you enjoy the image.

Image A: NGC6888_AP175dswNM_HORGB_LfromHO_crop 2500px-sq
Image B: NGC6888_AP175dswNM_HOx 2500px-sq
Image C: shows wrapping of blue haze

Alex Woronow

Final
Original
B
C

B

Title: HOx

Description: Uses extracted Ha and OIII emission lines mapped to true color

Uploaded: ...

C

Title: RGBHO little processed

Description: A lightly processed version showing the wrapping of blue haze (mostly OIII) above the main mass of the nebula)

Uploaded: ...

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Status	Advanced success
Started	...
Astrometry.net job	6195296
PixInsight job	TGTRV3SMLIT0D47K05XZ47I199YLA5LI
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	20h12m41s.770
RA (top/left)	20h11m09s.660
RA (top/right)	20h11m14s.493
RA (bottom/right)	20h14m13s.334
RA (bottom/left)	20h14m09s.827

Dec (center)	+38°18′54″.32
Dec (top/left)	+38°36′02″.80
Dec (top/right)	+38°00′50″.17
Dec (bottom/right)	+38°01′39″.70
Dec (bottom/left)	+38°36′52″.68

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