The Spitzer Adaptation of the Red-sequence Cluster Survey ( SpARCS ) is a z ^ { \prime } -passband imaging survey of the 50 deg ^ { 2 } Spitzer SWIRE Legacy fields , designed with the primary aim of creating the first large , homogeneously selected sample of massive clusters at z~ { } > ~ { } 1 .
SpARCS uses an infrared adaptation of the two-filter cluster red-sequence technique .
In this paper we report Keck/LRIS spectroscopic confirmation of two new exceptionally rich galaxy clusters , SpARCS J161315+564930 at z = 0.871 \pm 0.002 , with 14 high-confidence members and a rest-frame velocity dispersion of \sigma _ { v } = 1230 \pm 320 km s ^ { -1 } , and SpARCS J161641+554513 at z = 1.161 \pm 0.003 , with seven high-confidence members ( including one AGN ) and a rest-frame velocity dispersion of \sigma _ { v } = 950 \pm 330 km s ^ { -1 } .
We also report confirmation of a third new system , SpARCS J161037+552417 at z = 1.210 \pm 0.002 , with seven high-confidence members and a rest-frame velocity dispersion of \sigma _ { v } = 410 \pm 300 km s ^ { -1 } .
These three new spectroscopically confirmed clusters further demonstrate the efficiency and effectiveness of two-filter imaging for detecting bona fide galaxy clusters at high redshift .
We conclude by demonstrating that prospects are good for the current generation of surveys aiming to estimate cluster redshifts and masses at z \gtrsim 1 directly from optical-infrared imaging .