The Heart Nebula, Fish-Forward Version (IC 1805 and IC 1795) (Rob Foster)

The Heart Nebula, Fish-Forward Version (IC 1805 and IC 1795)

Revision title: The Heart Nebula, Fish-Forward Version (Draft 3)

The classic orientations of The Heart Nebula (IC 1805) is with the "V" of the heart at the top of the image, replicating the classic heart shape. However, this always relegates the Fishhead Nebula (IC 1795) to the 5:00 position where it is not as easy to appreciate. Another less common orientation is the more anatomically correct one, that finds the Fishhead Nebula placed at 1:00, and to my eye, this represented a heart even better with the smaller atrial cavities above and larger ventricular cavities below. This 2-panel mosaic orientation I have chosen places the IC 1805 more obliquely so that the IC 1795 can be seen in its pisciform glory as a more easily recognized fishhead. This image represented a couple of firsts for me using Russel Croman's excellent StarXTerminator tool to remove and then add back in later in the processing (in addition to his excellent NoiseXTerminator). I evaluated several workflows, and found that the image was easier to process with better stars if removing the stars after stretching once non-linear; they just looked better (morphology and color) than with the linear extraction. I also evaluated whether straight PixelMath addition back in or a blend mode using Screen (or negative multiply) as the Overlay Mode. What you see is the result of that Screen blending. I am very glad I did not upload the original versions, and instead am happy to share this version. The stars look so much better and less bloated that I am now re-evaluating previous uploads for revision! I was particularly happy with the color brought out in the open cluster NGC 1027 on the bottom right.

Original
B
Final
C

B

Title: Revised Heart and Fishhead Nebula (IC 1805 and IC 1795

Description: After processing the Soul Nebula, I went back and reprocessed this Heart and Fishhead Mosaic with more aggressive placement of DBE selection points; in the original mosaic, I didn't place any points on anything red, and I think that ended up including too much artifact. I am Still not happy with the visible merge band running vertically through the middle of the image, and this really doesn't show up until late in processing so I am not sure what I am doing wrong. I did use dnaLinearFit script after initial DBE before doing any mosaic construction, which was created using Photometric Mosaic script. Still, I think it looks better than the original draft.

Uploaded: ...

C

Title: The Heart Nebula, Fish-Forward Version (Draft 3)

Description: Bothered by the persisting gradient between the two images in version 2, I went back in PI and ran a gentle Canon Banding Reduction script, and although I do not think the vertical banding was from the sensor, it did help with the stark line differentiating the backgrounds.

Uploaded: ...

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Status	Advanced success
Started	...
Astrometry.net job	6378556
PixInsight job	RTAAU46HKEAUDX1ZP4BIDYPC4OCJUKTO
PixInsight queue size	n/a
PixInsight stage	TASK_LOG

RA (center)	02h33m27s.15
RA (top/left)	02h22m45s.64
RA (top/right)	02h43m51s.46
RA (bottom/right)	02h44m54s.11
RA (bottom/left)	02h22m14s.45

Dec (center)	+61°15′50″.1
Dec (top/left)	+60°09′20″.6
Dec (top/right)	+60°07′18″.3
Dec (bottom/right)	+62°18′53″.6
Dec (bottom/left)	+62°21′05″.10

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