added two more panels to Carina in hydrogen alpha
astrodon ha with the baby q and ASI 1600 mono.
90/90/60/60
need to sort out that gradient https://astrob.in/eix9zz/0/
Guiding looks good to me. Bottom right panel is spot on. Other three are out. Your field is flat as well so all good. Reshoot the other panels and you'll have a good one.
Guiding may be ok. The corner elongated stars you are probably looking at seem more like coma to me. That is because the star shapes will most likely be off until you hit good focus. I see this on the RHA sometimes, corner stars look a little odd but then are perfect when focus is closer.
FSQ are prone to focus shift with temperature changes. Every drop of 1C you need to refocus or set up temperature compensation on your focuser if you have one.
Separate from the above there appears to be some tilt as the top right hand stars are more out of focus than the top left. This will also add to the elongated stars in the corners.
Some of the image is quite sharp.
These fast petsvals give great results but they are a bit of a task master. They give such small stars that they can appear to be in focus when they are not.
I use 2x2 binning to focus and if I really want to be sure I check a 1x1 full download. That is very revealing.