LRGB - color cast in stars

It could be the case you have a bit of abberation or the stars in the green channel are just a bit larger. There is a way to try to align these, using the "align channels" option in tab 2 all the way down. Add calibration data to your lights (load in all of them), select this option and save them. Then clear the data in APP and reload these files (without calibration data) and process them.

If that doesn't work well, you could remove the green with the HSL selective color tool and pick a range where you're mainly working on the stars.

Thank you. I am now in the process of saving the frames. I now have the problem that I get the same message several times (probably for all channels HaLRGB):

I have for all lights, always flats, and for all flats, always dark flats as well. But why do I get the message? Because I have no bias frames? Or is there really something wrong with my dark frames?

Do you use a dark or bias for the lights as well?

Oh right, i fogotten to add the darks. But after i do this, i get the same messages. 

APP unfortunately does not provide good clarity when you have multiple nights with different filters.

I have assigned the darks to all LRGB (5min) and Ha (10min). In each case to all session, but in each case only to the associated filters.

For flats you do need a bias or flatdarks as APP needs to know the background signal. For the lights you can use darks which have the bias signal in them.

I add the Darkflats. 

Mmm, that is interesting. If the flats do behave properly on the lights then I guess you can ignore the warning. Maybe interesting to have a look at that as well data-wise.

Thats really strange.

It can happen that I forget the dark frames for a channel. But I have received the message several times, probably for each channel. Maybe there is a bug here when you do this via panel 2 at the bottom

I continued, and now two points:

- I have additional exposures for the red channel, which I previously left out to keep the channels in balance. I have now stacked these as well. And the end result is much more red than before. There are about 3 hours of additional red.

- I'll have to stack this again without the extra red. But it seems that the correction has helped somewhat, though not 100%. Something is still visible on the upper left side of the stars. 

The odd thing. This is not the case with the yellow stars! Or it is not so noticeable

- The flats on my green channel don't seem to work, I have a gradient there. Maybe that is affecting the stars?

Green:

Blue:

Red:

Luminance:

H-alpha:

Mmm, yes, with star color correction you should get a better balanced result color-wise. The small artefact you now have left I think is just something that's in the data, it seems like the alignment of channels really helped here so that's good. The small gradient that's left shouldn't affect the stars no, you can remove that with the LP tool as well very nicely.