Comet preset (limited extra)

Comet preset (limited extra)

IMPORTANT: The Comet Preset is an advanced Nebulb feature with limited access. It’s currently available only for Nebulb users who have a valid license (trial or official) created before November 3rd, 2025.

Why this preset exists

The main difficulty when processing comets is that they move differently from the stars (because of their proximity to Earth). Then, if your images are aligned using only the stars, the comet will appear blurred in the final result.

To avoid that, Nebulb includes this extra feature that aligns all images specifically on the comet instead of the stars—so the comet remains perfectly sharp in the final stacked image.

Step-by-step guide to process a comet in Nebulb:

1. Import your images

You can import images in several ways:
  1. Using the two buttons in the top-left corner
  2. Through the Image menu
  3. By dragging and dropping files or folders directly from Windows Explorer or macOS Finder
  4. Or even from any image viewer that supports drag & drop.


2. Select the “Comet (extra)” preset



3. Check if you used a star tracker

If you captured your images using an equatorial mount (star tracker), make sure to check the box “Capture with star tracker”.



4. Select the exclusion mask (“planet” button)



5. Draw a circle over the comet

Select the brush tool and, zooming in on the comet, draw a circle around its brightest area.



Tip:
  1. To zoom in while the brush is selected, right-click and hold to pan the image.
  2. You can adjust the brush radius using your mouse wheel.


6. Define the sky mask (if necessary)

If your image also includes landscape elements (like ground), you’ll need to define the sky mask as usual (using the three stars button).

For more details, check this article:

Note: If your image is entirely sky (like in this example), you don’t need to define a sky mask. Nebulb will automatically assume that the image contains only sky.

7. Run the stacking process

Now you can start the stacking. During this process, Nebulb will align all frames on the comet (not on the stars), resulting in a perfectly sharp comet in the final stacked image.



Note: When you start stacking, Nebulb will ask you to save your project first so that all stacking results are stored in that file.

8. Apply your desired processing adjustments

Once the stacking process is complete, the tool panels on the right side of Nebulb will be enabled, and you can apply any adjustments you want.

Here’s the result after stacking — the comet appears sharp (and not the stars), since the alignment was done specifically on the comet, which moves differently from the stars.



Because the final image also has very low noise (thanks to Nebulb’s stacking), you can now apply a strong light pollution reduction to bring out all possible details from the comet.




INFORMATION: This image of Comet C/2025 A6 Lemmon was captured at dawn on October 5th, 2025, in a highly light-polluted urban area. At that time, there were still several weeks left before the comet’s predicted brightness peak (expected in late October to early November).





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