Atacama Cosmology Telescope (ACT)

Side view of ACT.

The Atacama Cosmology Telescope (ACT) is a 6 meter telescope designed to map the Cosmic Microwave Background (CMB) over a large sky area with an angular resolution of 1 arcmin. The instrument observes at three frequencies (148, 218, and 277 GHz) in order to separate primary CMB anisotropy from the Sunyaev-Zeldovich effect and other secondary anisotropy sources. In order to minimize disturbance from atmospheric effects, the telescope is situated on the Atacama Plateau in northern Chile, at an elevation of 5190 m. More detailed specifications of ACT may be found at

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. Alan P. Smale
LAMBDA Director: Dr. Eric R. Switzer
NASA Official: Dr. Eric R. Switzer
Web Curator: Mr. Michael R. Greason