That is true they are feint to civilizations that don't have the capacity to view them because of technological constraints. Those are exactly the civilizations

That is true they are feint to civilizations that don't have the capacity to view them because of technological constraints. Those are exactly the civilizations you don't care about anyways, as they wont have the capacity to visit the site at that technological level nor respond with a signal in that general direction. So the beacon you place is trying to attract attention from a specific tech civilization you are interested in (from their perspective). Also when i say beacon i mean the green star. But not an active beacon, you place a dump particle swarm around the star that refracts light in to the green spectrum that's not possible by natural star type of deal. So energy wise not too intensive once you get the particles around the star. But there could be other methods as well that have nothing to do with green stars. For example another "beacon" could be augmentation of some sort near the most interesting objects in the universe... the black holes at the heart of almost every galaxy. You know as a conscious entity that others will look in that general direction as that is the most interesting place in the "neighborhood" so it warrants to do something round those parts to attract attention.