Following a period of voting by Fedora contributors, the Fedora 19 codename was determined based upon popular vote. The list of possible codenames was again unique, similar to Fedora 17 being codenamed the Beefy Miracle.
In the end, the Fedora 19 codename receiving the most popular votes was Schrödinger's Cat thereby making it the next codename to succeed the Spherical Cow. Schrödinger's Cat secured 1876 votes while Higgs Boson was in second with 1620 votes and Tiddalik was in third with 1012 votes. Other top contenders included Loch Ness Monster, Newtonian Dynamics, Martian Blueberries, and Parabolic Potassium.
Confirmation of the Fedora 19 codename can be found in this mailing list post.