ACT2 DR4 CMB HiPS

The Atacama Cosmology Telescope (ACT) is a six-meter diameter telescope on Cerro Toco in the Atacama Desert of northern Chile (image above by Jon Ward). It is designed to make high-resolution measurements of the cosmic microwave background (CMB) temperature and polarization anisotropies and detect massive galaxy clusters via the thermal Sunyaev Zel'dovich (tSZ) effect. Reconstruction of the CMB lensing potential will play a key role in the cosmological detection of neutrino mass, and measuring the imprint of primordial gravitational waves in B-mode polarization could provide unique insights into the early universe and quantum nature of gravity. The majority of the DR4 products use data collected from 2013-16. DR4 also includes data collected from 2008-10. The second-generation, polarization-sensitive receiver ACTPol observed between 2013 and 2016. The four-year survey consists of 17,000 square degrees of the sky mapped at 98 and 150 GHz, with the deepest 600 square degrees at a noise < 10 uK-arcmin.