The targets are special version of the normal enemy which simaris will inform you if the target will spawn in that mission.
They will have blue outline and zooming in with simaris's scanner will mark them and show 4 scanning spots.
Once you scanned all 4 spots, it'll go boom!
edit: I've just noticed that when i zoom in with simaris's scanner, there will be some blue light thingy floating around. These lights are actually a path that lead me directly to the target.
So, yeah, we can just mindlessly follow them lights and not actually hunting anything.