Balloon telescope reveals new clues about black hole Cygnus X-1
A high-altitude balloon carried the XL-Calibur telescope to study X-rays from the Cygnus X-1 black hole. The mission captured the most precise polarisation data yet, revealing how superheated material behaves near the black hole. It also observed the Crab pulsar and set the stage for a larger follow-up mission from Antarctica in 2027.