Blazars are a special case of "active galaxies" - those whose supermassive black holes spray out great quantities of light across the whole electromagnetic spectrum as they feed on surrounding matter.

BBC: Blazar Markarian 421's flare-up is cosmic coincidence

Three video pictures of the operation streamed on the screen one from a camera in the operating light, one from a wide-angle room camera, and one with the feed from the anesthesia monitor.

NEWYORKER: Personal Best