Probing Radio Intensity at High-Z from Marion: 2017 Instrument

We introduce Probing Radio Intensity at high-Z from Marion (PRI ZM), a new experiment designed to measure the globally averaged sky brightness, including the expected redshifted 21cm neutral hydrogen absorption feature arising from the formation of the first stars. PRI ZM consists of two dual-polarization antennas operating at central frequencies of 70 and 100MHz, and the experiment is located on Marion Island in the sub-Antarctic. We describe the initial design and configuration of the PRI ZM instrument that was installed in 2017, and we present preliminary data that demonstrate that Marion Island offers an exceptionally clean observing environment, with essentially no visible contamination within the FM band.