Spectroscopic redshifts of gal. in SPT-CLJ0615-5746

Using Nod & Shuffle multislit observations with LDSS-3 on Magellan, we identify ~50 cluster members and derive a cluster redshift of z_c_=0.972, with a velocity dispersion of {sigma}=1244+/-162km/s. We calculate a cluster mass using a {sigma}_200_-M_200_ scaling relation of M_200_=(9.6+/-3.5)x10^14^M_{sun}_, in agreement with previous, independent mass measurements of this cluster.

In addition, we examine the kinematic state of SPT-CLJ0615-5746, taking into consideration prior investigations of this system. With an elongated profile in lensing mass and X-ray emission, a non-Gaussian velocity dispersion that increases with clustercentric radius, and a brightest cluster galaxy not at rest with the bulk of the system, there are multiple cluster properties that, while not individually compelling, combine to paint a picture that SPT-CLJ0615-5746 is currently being assembled.