We report the discovery of an IR-selected galaxy cluster in the IRAC Distant Cluster Survey ( IDCS ) .
New data from the Hubble Space Telescope spectroscopically confirm IDCS J1433.2+3306 at z = 1.89 with robust spectroscopic redshifts for seven members , two of which are based on the 4000Ã Â break .
Detected emission lines such as [ O ii ] and H \beta indicate star formation rates of \gtrsim 20 M _ { \odot } yr ^ { -1 } for three galaxies within a 500 kpc projected radius of the cluster center .
The cluster exhibits a red sequence with a scatter and color indicative of a formation redshift z _ { f } \gtrsim 3.5 .
The stellar age of the early-type galaxy population is approximately consistent with those of clusters at lower redshift ( 1 < z < 1.5 ) suggesting that clusters at these redshifts are experiencing ongoing or increasing star formation .