We present confirmation of the cluster MOO J1142+1527 , a massive galaxy cluster discovered as part of the Massive and Distant Clusters of WISE Survey .
The cluster is confirmed to lie at z = 1.19 , and using the Combined Array for Research in Millimeter-wave Astronomy we robustly detect the Sunyaev-Zel ’ dovich ( SZ ) decrement at 13.2 \sigma .
The SZ data imply a mass of M _ { 200 m } = ( 1.1 \pm 0.2 ) \times 10 ^ { 15 } M _ { \odot } , making MOO J1142+1527 the most massive galaxy cluster known at z > 1.15 and the second most massive cluster known at z > 1 .
For a standard \Lambda CDM cosmology it is further expected to be one of the \sim 5 most massive clusters expected to exist at z \geq 1.19 over the entire sky .
Our ongoing Spitzer program targeting \sim 1750 additional candidate clusters will identify comparably rich galaxy clusters over the full extragalactic sky .