How to get rid of strange gradient in 3-image mosaic

Did you use LNC as well?

@vincent-mod  Yes. 1st degree with 3 iterations

Mmm, could you show a screenshot of the integrations per session? So what the separate panels look like?

Stacks of session 1, 2, and 3

Mm, not much to see really. Could you upload like 5 subs per panel to our server, so I can try as well?

Go to https://upload.astropixelprocessor.com and use upload as username and upload as password.

Create a directory named “tailspin45-mosaicissue” and upload in there. Thank you!

@vincent-mod Done. Created three subfolders, one for each session, with the requested 5 subframes for each session.

Thanks! I forgot to ask, but could you also upload master calibration data to the same folder?

@vincent-mod Done. Master dark and master flat, didn't make or use a master dark-flat

Thanks Tom, give me a day to process. Bit busy at the moment, sorry.

Sorry, took a bit longer. So I was confused as I got a 2 panel result. But it seems you accidentally uploaded the same data across 2 sessions. 🙂

You're right. Session 1 files are now the proper ones.

Thanks Tom, I'll work on it this weekend and come back to you then.

Hi Tom, so I had a go with the mosaic. First without calibration data (as that can be a cause of many issues).

I used mosaic integration, advanced normalization, scale stop to 10, LNC and MBB at 20% (there is a lot of overlap, so much that it's almost not a mosaic actually).

First result;

Clearly a lot of light pollution, so I'll try your flats after this.

Light pollution correction, going from the outside-in with the boxes;

And without all those boxes;

I added some saturation, with higher contrast as well. Seems to work, though could be better, let me try with some calibration data.

Ok, now with flats, they did help a bit, but you seem to have quite a lot of light pollution issues over there unfortunately. I think correcting the panels first nicely and then making the mosaic will work better. Now I just cropped a part that wasn't behaving nicely, it's still ok, but if we could manage the pollution better that would help a lot.

Thanks for your efforts. they certainly turned out better than mine!.

I live in a Bortle 7-8 area and try to manage light pollution with an Optolonhg L-Pro filter.

But the bigger issue may be local incident light from a street light across the street and bright lights at a desalinization plant about 1500m away.

Again, thanks for your help!

Oeh yeah that's not very nice indeed. I would also look into using narrow-band filters, that will help a lot in your situation. Have a look at a nice H-alpha filter, maybe you can borrow one from someone?

Is my above answer helping you to get the same result? That would be great if so. 🙂

@vincent-mod Just to wind up the topic here, I've hung a black curtain to block the nearby light sources, and have invested in an L-eXtreme narrowband filter.

Results so far look promising. Case closed, I say, and thanks for the help.

I'll post an image here if, indeed, the problem is solved.

That's great to hear Tom! If you need any help processing that kind of data, let us know!

Rotated 90º

Excellent! That is a huge improvement isn't it!