Amaterasu rasengan <.< There are more types of those than levels of power ups in dragon ball Z, yo >.>
Also on the matter of Amaterasu, we've seen it dodged by A and blocked by Gaara's sand. Neither of whom can sense chakra (that we're aware of, although gaara's shield is described as automatic....x.X) so who knows how in the world it works, this manga is full of contradictions at this point xD
I think it's safe to say that for SL though we don't go with the instantaneous production of fire on a target because that's essentially...auto-hitting. Unless we're taking into account those two instances I mentioned above in which case....there's something other than chakra flow (with dojutsu used to see it of course or sensor type people) that gives away it's use. o.O