What would cause this in DSS?

[JB80]

Just running a couple of stacks and the second one has come out all weird like this.

What would cause this as there are no artifacts in the subs they look similar to the first lot which stacked OK and all I changed from the first batch of pics was the location.

I have tried with darks and without and grabbing different pics from different times in the run and this still shows up to some extent.

[JamesF]

It looks a bit like a bright light source just out of the field of view to me. Are there any obvious artefacts in the individual subs?

James

[emadmoussa]

Astray light perhaps. Or one of the ghosts from James's house..

[JB80]

Nothing obvious apart from two faint perseids, it's funny you say that though but a little smudge appeared about halfway through the 1st imaging run and was gone by the end.

That stacked fine though and I can't see it on the second batch.

It could be a light source, it was my first thought but again there is no obvious brightening to one side of the subs or anything like that.

[JB80]

I will also accept ghosts as a valid answer.

Space ghosts.

[12dstring]

Are the dX and dY offsets and angles calculated all fairly small/similar?

Perhaps something is throwing off the alignment.

The stars disappearing towards the left and the dark pattern on the left look like it hasn't been stacked evenly with all of the subs aligned.

[JB80]

I'll have to run it through again and check that.

[ollypenrice]

The mathematical appearance of the patterns, which look like 'curve stitching,' make me think this is a purely digital phenomenon. It doesn't look anything like stray light to me. In other words it's being created in the software.

Olly

[JB80]

You may be right, I did manage to get one unaffected stack out of about 8 tries but it didn't want to do it without dropping a heap of subs from the stack.

The bit that gets me is it only happens on that bunch of subs not the ones taken minutes before in a different location.

It's no great loss I just want to avoid it happening again if it can be helped.

[Shibby]

I've seen this before... Wish I could remember the exact cause, but it may have been something to do with changing the debayer method *after* registering the images. Try either re-registering them all or changing your RAW debayer settings.