IC 1805: The Heart Nebula - A 6 Panel Mosaic

28 August 2022

I already captured the Heart Nebula once or twice (here, here, here and here), but up until recently I only had an unmodified stock DSLR to do so. But the nebula contains a boatload of hydrogen alpha any new attempt using my dedicated astro camera promised a much better result.

So the heard nebula was a natural choice for me to take on this summer. The only problem is that the sole telescope that I can fit the camera to is my Skywatcher 130 PDS which has a way too high magnification to fit the whole nebula within one frame. That should not be a problem (I thought) and set up my scope to take a two-by-three mosaic of the region.

Acquiring the images was no problem at all: The plan created with telescopius and the actual execution was just as easy as described in my first post about taking a mosaic image. The problems started when I wanted to stitch the panels together. Finally, I settled on some different settings within the gradient merge tool (average combination instead of an overlay combination) and preprocessing (DBE, EZ Denoise) each panel before attempting to stitch them. But due to the extreme difference in elevation of the object between the first and last panel, I had some quite visible borders and gradients in my final image. Using the dynamic background extraction from Pixinsight did not work for me as expected and I had to search for another tool.

This I found in GraXpert which did a wonderful job extracting the gradient and hiding the edges of the panels. Finally, after several attempts of getting a processable image out of my raw data, I had a result that was feasible and I could continue to process the image to my liking.

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