Melotte 15 / IC 1805 - The Heart of The Heart Nebula (Steve Ludwig)

Melotte 15 / IC 1805 - The Heart of The Heart Nebula

I recently imaged the center of the heart nebula when I was waiting for M42 to reach a sufficiently high altitude. That's why I only got a little more than three hours of integration time. Considering that my scope is not the fastest and that I used an unmodified DSLR without filters, the result is not too bad, I think. Please let me know what you think about it.

Equipment

- Main scope: Bresser Messier 10" Newton (254/1270)

- Main camera: Nikon D3300 (unmodified)

- Guide scope: Orion AC 50/162 Deluxe Mini

- Guide camera: ZWO ASI 290MC

- Mount: Skywatcher EQ6-R

- Explore Scientific HR coma corrector

Acquisition

- 41 lights x 300 s = 3 h 25 min

- no dark, flat, bias frames

- no filters

- ISO 800

- Bortle 4

Processing

- stacked in DSS

-> bilinear debayer method & median kappa sigma clipping

- unmodified TIF opened in PixInsight

-> STF stretch

-> crop

-> dynamic background extraction

-> background neutralization

-> color calibration

-> histogram transformation

-> SCNR green to remove greenish noise

-> use of starnet++ module to separate stars and background

Stars

-> curves transformation to increase saturation of stars

Background

-> red channel extraction

-> range selection to create a smooth mask from the red channel image that contains the reddish hydrogen alpha regions

-> application of this mask to the original (color) background image

-> masked curves transformation to increase saturation of red hydrogen alpha regions without increasing color noise of the background

-> masked local histogram transformation to increase contrast of hydrogen alpha regions

-> pixel math to recombine stars and background

-> TGV denoise to reduce noise

-> resample 50%

-> ACDNR with integrated lightness mask to reduce noise further

-> histogram transformation

-> rotation to ensure that star diffraction spikes are vertical/horizontal

-> dynamic crop

-> background neutralization to remove an overall reddish tint of the image

-> saved as jpg

Original
B
C
Final
D

B

Description: Added another background neutralization as final processing step. Let me know which revision you like more. Looking at my widefield image of the heart nebula, I tend to think that the original version might look a bit more natural.

Uploaded: ...

C

Description: For the latest revision I applied an additional run of "TGV Denoise" on the background and did some curves/histogram fine-tuning to bring out the nebulosity more.

Uploaded: ...

D

Description: In revision D, I applied a further instance of ACDNR to reduce the noise of the background. This in turn allowed me to increase the background brightness a bit.

Uploaded: ...

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Status	Advanced success
Started	...
PixInsight job	WKL2GWAJH7Y0XT8LWY9ET4E8GR3N8L4T
PixInsight queue size	n/a
PixInsight stage	n/a

RA (center)	02h35m01s.33
RA (top/left)	02h30m23s.85
RA (top/right)	02h36m44s.50
RA (bottom/right)	02h39m38s.60
RA (bottom/left)	02h33m14s.48

Dec (center)	+61°23′00″.7
Dec (top/left)	+61°23′16″.4
Dec (top/right)	+60°52′18″.10
Dec (bottom/right)	+61°22′09″.1
Dec (bottom/left)	+61°53′40″.4

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