what is the purpose of the event horizon telescope
Event Horizon Telescope The Event Horizon Telescope (EHT) is a project to create a large telescope array consisting of a global network of radio telescopes and combining data from several very-long-baseline interferometry (VLBI) stations around the Earth. The aim is to observe the immediate environment of the Milky Way's supermassive black hole Sagittarius A*, as well as the even larger black hole in Messier 87, with angular resolution comparable to the black hole's event horizon.[1][2][3][4][5]
Refracting telescope The design Galileo Galilei used in 1609 is commonly called a Galilean telescope. It used a convergent (plano-convex) objective lens and a divergent (plano-concave) eyepiece lens (Galileo, 1610).[6] A Galilean telescope, because the design has no intermediary focus, results in a non-inverted and upright image.