StarXTerminator struggles with saturated stars in NGC 6960 processing - Forums

Topic starter

5 hours ago

I’m running into a pretty specific issue while processing a starless version of NGC 6960 (Western Veil) with StarXTerminator, and I’m curious if anyone has found a better workflow for this kind of target.

The problem is that some large, saturated stars are not being fully recognized as stars, so parts of them remain in the starless image, while the stars image ends up with incomplete or partially “eaten” stars.

The problematic stars are mainly those with:

large halos
saturated cores
nebula filaments crossing very close to the star

My setup:

Sky-Watcher Evostar 72ED
ZWO ASI585MC Pro
PixInsight workflow
StarXTerminator tested both on linear and non-linear data
Large Overlap enabled

I already tried:

running StarX on linear data
downsampling before StarX
BlurXTerminator before StarX
Large Overlap
pre star-reduction
double-pass StarX workflows

…but the behavior stays very similar.

What I’m noticing is that StarX seems to interpret part of the stellar halo as actual Veil nebulosity.

At this point I’m considering a different approach:

creating a manual mask only for the residual stars
applying local sharpening/star reduction only on the problematic stars
or rebuilding/fixing those stars directly in the stars image

Has anyone experienced the same issue on filamentary nebulae like the Veil / Cygnus Loop?

I’d especially like to know:

if there’s a more reliable workflow
whether full starless separation is simply not ideal for these targets
or if local manual correction is basically the best solution

I’ll attach a crop showing the issue.

Apparently removing stars from the sky is still harder than removing wrinkles from social media selfies.

📷 masterLight_BIN-1_3840x2160_EXPOSURE-120.00s_FILTER-NoFilter_RGB_autocrop.jpg📷 NGC_6960.jpg

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Obbe J

5 hours ago

I know it’s not ideal, but if nothing else works, you can always try to clone stamp these away. If not done very carefully though, it can later on create horrible looking artifacts.

Werner Stumpferl

4 hours ago

make one with starnet++ and one with starxterminator.

Blink both and copy the better areas to one picture.

You will see, that especially starxterminator looses some faint areas because no software is perfect. So take the best from both for one picture.

If there are halos in both … try what Obbe J has told.

Igor Fulvi

Topic starter

4 hours ago

I had already thought about the Clone Stamp, but if I'm not mistaken this allows me to "delete" the star and not "clone" it in the "starry" image that will be used to recompose everything, in this way the final image will have fewer stars, am I wrong?

Jan Erik Vallestad

3 hours ago

Obviously this was only done with a screengrab from here, and I apologise in advance as I don’t like doing this without consent, but;
This isn’t so bad, basically only one problematic star partially left behind. Correct only, followerd by SXT using large overlap. But the permanent fix to your issue is to root out what causes the problems in the first place. Several things look off in your image.

1. Your backfocus is off, this may not be a dealbreaker to you - but processing isn’t going to fix the edges, it’s going to attempt to mask them - but they will not look as good.

2. You didn’t mention what kind of filter you are using, the 585MC only has an AR cut window, so you will at the very least need a UV/IR cut filter in front of it. Not using one will result in star bloat and questionable focus.

If you did use a filter then maybe that filter is no good.

3. You don’t mention gain, but HCG mode kicks in at 200. This is pretty high and you should use the histogram to adjust your exposures accordingly to avoid saturating the stars if this is what’s happening in your case. There’s basically no reason to push exposure lengths too far. If you still want to use longer exposure times then you should be reducing gain but at the possible cost of added noise.

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TiffsAndAstro

3 hours ago

I'd say it handles them pretty well.

With my 72ed and 533 it seemed a lot worse.

As said above, you can clone stamp them out, but that might make thos stars look worse overall. Might not :)

Also you could try giving the image a bit of stretch before removing the stars. This might help.

Might not :)

To be fair this target has pretty horrendously bright stars, second only to Alnitak near horse head/flame nebula in my limited experience :(

This is an ill advised 4 panel mosaic taken not long after getting a mount and filter. Maybe you smaller pixels don't help, but I'm not sure about that :) maybe helpful comparison.

https://telescopius.com/pictures/view/199619/deep_sky/sh-2-103/veil-nebula-4-panels-80mins-per-panel/by-tiffsandastro

I don't think you have anything to worry about.

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Igor Fulvi

Topic starter

1 hour ago

TiffsAndAstro · May 18, 2026, 11:30 AM
I'd say it handles them pretty well.
With my 72ed and 533 it seemed a lot worse.
As said above, you can clone stamp them out, but that might make thos stars look worse overall. Might not :)
Also you could try giving the image a bit of stretch before removing the stars. This might help.
Might not :)
To be fair this target has pretty horrendously bright stars, second only to Alnitak near horse head/flame nebula in my limited experience :(
This is an ill advised 4 panel mosaic taken not long after getting a mount and filter. Maybe you smaller pixels don't help, but I'm not sure about that :) maybe helpful comparison.
https://telescopius.com/pictures/view/199619/deep_sky/sh-2-103/veil-nebula-4-panels-80mins-per-panel/by-tiffsandastro
I don't think you have anything to worry about.

Congratulations! It seems like a great thing to me

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Igor Fulvi

Topic starter

49 minutes ago

Jan Erik Vallestad · May 18, 2026, 11:26 AM
Obviously this was only done with a screengrab from here, and I apologise in advance as I don’t like doing this without consent, but;
This isn’t so bad, basically only one problematic star partially left behind. Correct only, followerd by SXT using large overlap. But the permanent fix to your issue is to root out what causes the problems in the first place. Several things look off in your image.

1. Your backfocus is off, this may not be a dealbreaker to you - but processing isn’t going to fix the edges, it’s going to attempt to mask them - but they will not look as good.

2. You didn’t mention what kind of filter you are using, the 585MC only has an AR cut window, so you will at the very least need a UV/IR cut filter in front of it. Not using one will result in star bloat and questionable focus.

If you did use a filter then maybe that filter is no good.

3. You don’t mention gain, but HCG mode kicks in at 200. This is pretty high and you should use the histogram to adjust your exposures accordingly to avoid saturating the stars if this is what’s happening in your case. There’s basically no reason to push exposure lengths too far. If you still want to use longer exposure times then you should be reducing gain but at the possible cost of added noise.

1. Why do you tell me the backfocus isn't correct? What do you mean? Sorry, but I'm quite a novice; I focused with the Bathinov mask and it was practically perfect.

2. You're right, I didn't specify the equipment clearly; the camera is an ASI585MC Pro (set at 0°C) with an Optolong l-eNhance filter.

3. The gain is indeed very high; I set it to 250 on purpose because this session was just a test; this session was definitely not intended to produce a good image, but rather to experiment... I only had two hours to spare and wanted to try out the new camera (previously I had the uncooled version) and the new filter. I decided to attempt the photo session, knowing that I had little time, so I turned up the gain too high.

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