Any time we talk about some subject its always the same . The discussion goes to the wrong direction. Limitations about telescopes , about networks , about computing power , about refraction, atmospheric conditions e t.c . .. I don't care them. The question is how does every gravitational pool of any object between the surveillancing aliens and our technique distort the original image coming from their distant planet for instance situated at the other end of the Milky way galaxy or in the begining of the open cluster of some other galaxies ? If that will help you I show you this interactive map . https://in-the-sky.org/ngc3d.php