The Cosmology Large Angular Scale Surveyor (CLASS) is an array of four microwave telescopes at a high-altitude site in Chile's Atacama Desert of Chile as part of the Parque Astronómico de Atacama. The CLASS experiment aims to probe reionization and primordial gravitational radiation by making precise measurements of the polarization of the Cosmic Microwave Background (CMB) on the largest angular scales over 75% of the sky (+30° declination to -76°) at 40, 90, 150, and 220 GHz.

A service of the HEASARC and of the Astrophysics Science Division at NASA/GSFC
Goddard Space Flight Center, National Aeronautics and Space Administration
HEASARC Director: Dr. Andrew F. Ptak
LAMBDA Director: Dr. Thomas M. Essinger-Hileman
NASA Official: Dr. Thomas M. Essinger-Hileman
Web Curator: Mr. Michael R. Greason