  The Unified Astronomy Thesaurus (UAT) is an open, interoperable and
community-supported thesaurus which unifies the existing divergent and isolated
Astronomy & Astrophysics vocabularies into a single high-quality,
freely-available open thesaurus formalizing astronomical concepts and their
inter-relationships. The UAT builds upon the existing IAU Thesaurus with major
contributions from the astronomy portions of the thesauri developed by the
Institute of Physics Publishing, the American Institute of Physics, and SPIE.
We describe the effort behind the creation of the UAT and the process through
which we plan to maintain the document updated through broad community
participation.
