SPECTROSCOPIC CONFIRMATION OF TWO MASSIVE RED-SEQUENCE-SELECTED GALAXY CLUSTERS AT z ∼ 1.2 IN THE SpARCS-NORTH CLUSTER SURVEY

The Spitzer Adaptation of the Red-sequence Cluster Survey (SpARCS) is a deep z'-band imaging survey covering the Spitzer Wide-Area Infrared Extragalactic Survey (SWIRE) Legacy fields designed to create the first large homogeneously selected sample of massive clusters at z > 1 using an infrared adaptation of the cluster red-sequence method. We present an overview of the northern component of the survey which has been observed with Canada-France-Hawaii Telescope (CFHT)/MegaCam and covers 28.3 deg(2). The southern component of the survey was observed with Cerro Tololo Inter-American Observatory (CTIO)/MOSAICII, covers 13.6 deg(2), and is summarized in a companion paper by Wilson et al. We also present spectroscopic confirmation of two rich cluster candidates at z similar to 1.2. Based on Nod-and-Shuffle spectroscopy from GMOS-N on Gemini, there are 17 and 28 confirmed cluster members in SpARCS J163435+402151 and SpARCS J163852+403843 which have spectroscopic redshifts of 1.1798 and 1.1963, respectively. The clusters have velocity dispersions of 490 +/- 140 km s(-1) and 650 +/- 160 km s(-1), respectively, which imply masses (M(200)) of (1.0 +/- 0.9) x 10(14) M(circle dot). Conformation of these candidates as bona fide massive clusters demonstrates that two-filter imaging is an effective, yet observationally efficient, method for selecting clusters at z > 1.