Very long baseline interferometry

technology

The technique that lets telescopes thousands of kilometres apart behave as one. Each station records the incoming radio signal with a timestamp from a hydrogen maser clock, and the recordings are later combined so that the interference between pairs of stations is recovered; the angular resolution is set by the separation between stations rather than by the size of any dish. No signal passes between the telescopes while they observe. The essential limitation is that such an array samples only a sparse set of points in the plane of spatial frequencies, so most of the information a filled aperture would collect is simply absent, and an image must be reconstructed by choosing among the many pictures consistent with the data. That is why the phrase "photograph of a black hole" is misleading: what is published is a reconstruction, and the discipline of the field is in demonstrating that the chosen reconstruction is not an artefact of the choosing. Not a place on Earth.

A technology is not a place. Drawing it on a map would assert something about the world that no stored fact supports.