Abstract

We present the temperature power spectra. of the cosmic microwave background (CMD) derived from the three seasons of data from the Atacama Cosmology Telescope (ACT) at 148 Ealiz and 218 GHz as well as the (Toss-frequency spectrum between the two channels. We detect and correct. for contamination due to the Galactic cirrus in our equatorial maps. We present the results of a number of tests for possible systematic error and conclude that any effects are not significant compared to the statistical errors we quote. Where they overlap we cross-correlate the ACT and the South Pole Telescope (APT) maps and show they are consistent. The measurements of higher-order peaks in the CMB power spectrum provide an additional test of the ACDM cosmological model, and help constrain extensions beyond the standard model. The small angular scale power sped rum also provides constraining power on the Sunyaev-Zel'clovich effects and extragalactic foregrounds. We also present a measurement of the CMB gravitational lensing convergence power spectrum at 4.6 sigma detection significance.