Charlie Hill from UC Berkeley working on the half wave plate for the Polar Bear 2b instrument, precursor to the SAT HWP Peter Ashton readies the SAT1 half wave plate for installation for first full test Peter Ashton from UC Berkeley installing the half wave plate (HWP) for SAT1 Peter Ashton from UC Berkeley installing the half wave plate with a mock saphire filter HWP power supply and control module The Cold Readout Assembly (CRA) installed in SAT1 the CRA Nicholas Galitzki SATR-1 Cryostat on cart with Nick Galitzki pulse tube cooler assembly Ground breaking for the Simons Observatory Lenslet array for a detector wafer lenslet integrated onto detector waver horn couple detector module Quadpole bolometer The LATR team at University of Michigan LATR assembly LATR assembled, focal plan side LATR sheilding