Maybe they have tech that shows them our radar scanning patterns, so they know where to be. And maybe other tech to make themselves less visible via vision, ie

Maybe they have tech that shows them our radar scanning patterns, so they know where to be. And maybe other tech to make themselves less visible via vision, ie, light bending or something like that. They might want to see how humans react to the possibility of aliens, without completely freaking the planet out by landing somewhere, walking out of a ship, and saying "take me to your leader".