You used eight telescopes for a week-long observation of black holes in April 2017. Which telescopes were used, and was it difficult to get so much observing time on all these telescopes?

We consider ourselves very fortunate that our science is widely viewed as compelling, and that many observatories supported the Event Horizon Telescope observations. The following radio telescope observatories were involved in our 2017 observations: ALMA (Atacama Large Millimeter/Submillimeter Array, Chile, Chajnantur Plateau,, APEX (Atacama Pathfinder Experiment, Chile, Chajnantur Plateau,, IRAM 30m (Institute de RadioAstonomie Millimtrique, Pico Veleta, Spain,, LMT, (Large Millimeter Telescope, Mexico,, SMT (Submillimeter Telescope, US, Arizona,, JCMT (James Clerk Maxwell Telescope, US, Hawaii,, SMA (SubMillimeter Array, US, Hawaii,, SPT (South Pole Telescope, South Pole, Coordinated (same-time) observations were also made in the X-ray and gamma-ray bands.