You can detect the presence of dragons and other draconic creatures within your line of sight and 120 feet, regardless of disguises, illusions, and alteration magic such as Polymorph. The information you uncover depends on the number of consecutive rounds you spend an action studying a subject or area. On the first round of examination, you detect whether any draconic creatures are present, but not their number, location, identity, or type. On the second round, you learn the number of such creatures as well as the general condition of the most powerful one. On the third and subsequent rounds, you make a DC 15 Intelligence (Arcana) check; if it succeeds, you learn the age, type, and location of one draconic creature. Note that the spell provides no information on the turn in which it is cast, unless you have the means to take a second action that turn.