In 2019, the Event Horizon Telescope (EHT) delivered the first resolved images of M87*, the supermassive black hole in the center of the giant elliptical galaxy Messier 87 (M87). Those images were produced using EHT observations performed in April 2017. Additional observations were required to investigate the persistence of the primary image feature and to quantify the image variability. To address this need, astronomers analyzed M87* data collected...
