Luminous red nova AT2025abao inadvertently imaged!
I just went back to my 4 hour exposure of M31 taken on October 27 and found the luminous red nova AT2025abao lurking there! It was only discovered 10 days prior to that. Luminous red novas are very rare, they are the result of a merging of two orbiting stars, rather than the end of a star's lifetime, or a cyclic expulsion of stellar "ash" that are the normal kind of nova. I've drawn arrows on these two crops from the original image Here's a wider image so you can see where to look: