Looks like a diffraction pattern to me. The way it flickers makes me think they're running some corrective algorithm that's struggling with some of the stars. (

Looks like a diffraction pattern to me. The way it flickers makes me think they're running some corrective algorithm that's struggling with some of the stars. (See the bottom left as well, they both appear to be bright sources and also on the edge of the field.) Also interesting to note how it seems to show up more when the image is crisper. No clue why that might be. https://en.wikipedia.org/wiki/Airy_disk https://en.wikipedia.org/wiki/Airy_disk