How many researchers contributed to making of the first black hole image?

The Event Horizon Telescope (EHT) Collaboration is a team of two hundred individual researchers situated at a number of research institutions around the world. The EHT is subdivided into different expert teams to address the different challenges of the coordinating a global research effort, such as phasing individual arrays to work as a single telescope of the global network, outfitting the telescopes at the different sites with new hardware and software purpose built for the EHT observations, post-processing the data in the correlator center, calibrating and validating the data, testing algorithms and computing images, interpreting the images obtained, producing numerical simulations to compare with the observations.

More than 200 researchers and engineers from 20 different countries and regions around the world are currently members of the EHT Collaboration. However, even more individuals have contributed to the pioneering work on the first image of a black hole over the different stages listed above, so the total number of co-authors of the main scientific publication, and winners of the 2020 Breakthrough prize in Fundamental Physics, is 347.