Finally an RGB image of comet #3IATLAS from images taken by #GeminiNorth during the 26 November #shadowTheScientists session: https://noirlab.edu/public/news/noirlab2532/ - the coma has become bluer due to more gas emission. Also published today: an X-ray image by XMM-Newton at https://www.esa.int/ESA_Multimedia/Images/2025/12/XMM-Newton_sees_comet_3I_ATLAS_in_X-ray_light with explanations in http://www.cbat.eps.harvard.edu/iau/cbet/005600/CBET005646.txt which also contains more 3I news.

Meanwhile the paper https://iopscience.iop.org/article/10.3847/2515-5172/ae2915 claims an upper limit for 3I's nucleus diameter of only some 750 meters from the measured non-gravitational acceleration (NGA) parameters: that would be waaay more stringent than the 5.6 km upper limit from early Hubble observations reported in https://iopscience.iop.org/article/10.3847/2041-8213/adf8d8 (where also a lower limit of 440 meters is stated).