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We present spectroscopic confirmation of five galaxy clusters at $1.25 < textit{z} < 1.5$, discovered in the $2500$ deg$^{2}$ South Pole Telescope Sunyaev-Zeldovich (SPT-SZ) survey. These clusters, taken from a mass-limited sample with a nearly redshift independent selection function, have multi-wavelength follow-up imaging data from the X-ray to near-infrared, and currently form the most homogeneous massive high-redshift cluster sample known. We identify $44$ member galaxies, along with $25$ field galaxies, among the five clusters, and describe the full set of observations and data products from Magellan/LDSS3 multi-object spectroscopy of these cluster fields. We briefly describe the analysis pipeline, and present ensemble analyses of cluster member galaxies that demonstrate the reliability of the measured redshifts. We report $textit{z} = 1.259, 1.288, 1.316, 1.401$ and $1.474$ for the five clusters from a combination of absorption-line (Ca II H$&$K doublet - $3968,3934$ {AA}) and emission-line ([OII] $3727,3729$ {AA}) spectral features. Moreover, the calculated velocity dispersions yield dynamical cluster masses in good agreement with SZ masses for these clusters. We discuss the velocity and spatial distributions of passive and [OII]-emitting galaxies in these clusters, showing that they are consistent with velocity segregation and biases observed in lower redshift SPT clusters. We identify modest [OII] emission and pronounced CN and H$delta$ absorption in a stacked spectrum of $28$ passive galaxies with Ca II H$&$K-derived redshifts. This work increases the number of spectroscopically-confirmed SZ-selected galaxy clusters at $textit{z} > 1.25$ from three to eight, further demonstrating the efficacy of SZ selection for the highest redshift massive clusters, and enabling detailed study of these systems.
(abridged) We present cosmological constraints obtained from galaxy clusters identified by their Sunyaev-Zeldovich effect signature in the 2500 square degree South Pole Telescope Sunyaev Zeldovich survey. We consider the 377 cluster candidates identi
We present the results of SPT-GMOS, a spectroscopic survey with the Gemini Multi-Object Spectrograph (GMOS) on Gemini South. The targets of SPT-GMOS are galaxy clusters identified in the SPT-SZ survey, a millimeter-wave survey of 2500 squ. deg. of th
We explore extensions to the $Lambda$CDM cosmology using measurements of the cosmic microwave background (CMB) from the recent SPT-SZ survey, along with data from WMAP7 and measurements of $H_0$ and BAO. We check for consistency within $Lambda$CDM be
We present Gemini and Keck spectroscopic redshifts and velocity dispersions for twenty clusters detected via the Sunyaev-Zeldovich (SZ) effect by the Planck space mission, with estimated masses in the range $2.3 times 10^{14} M_{odot} < M < 9.4 times
We present three maps of the millimeter-wave sky created by combining data from the South Pole Telescope (SPT) and the Planck satellite. We use data from the SPT-SZ survey, a survey of 2540 deg$^2$ of the the sky with arcminute resolution in three ba