Strange stacking artefacts in APP

[edarter]

Hi,

I know APP isn't the most commonly used stacking software but I've usually found it to be very very good until now, but I'm getting a strange issue when trying to stack some data I have taken this week of the Soul nebula. The resulting stack has odd coloured pixel artefacts in clusters over the image, red and blue predominantly but some green as well. Its a 2 panel mosaic but I don't think its to do with that as the artefacts are over both panels, not just the overlap. Any thoughts / suggestions as to what could be causing this would be greatly appreciated!

Thanks
Ed

[almcl]

They look very much like hot pixels.  The repeated similar pattern between the different colours tends to support this.

Don't know enough about APP to suggest a remedy, but in other stacking software a Sigma clip stack would normally eliminate this, provided there are enough sufficiently dithered subs of course.

There seem to be about 20 pixels, or so, if this corresponds to the number of stacked subs it is probably a bit low for an effective sigma clip.  Can you get some more data?

[ONIKKINEN]

Yep, looks like hot pixels spaced out by random dithers.

Decrease the hot pixel sigma in the integration tab until they go away, try 3 for starters.