Round 3 answers:BETELGEUSE
Each of these answers is an object of size (or wavelength) approximately 10n meters, where 10n is one of the fourteen orders of magnitude from the previous two rounds. Each order of magnitude in the previous two rounds produced one letter of its round's meta answer. Use those letters again to spell out the solution:
|GAMMA RAY||10−12||⇒ O|
|STINGRAY NEBULA||1015||⇒ N|
The supermeta solution for the Katamari Damacy gameworld is therefore OBERON.