Atacama Cosmology Telescope (ACT)
CMB Hit-Count Maps 2008 Data
These files contain combined hit-count maps for each pixel of Atacama Cosmology Telescope (ACT) maps of the southern stripe field, observed during the 2008 season, in the 148 GHz band, and produced for the first ACT data release in March 2012. They are to be used with the associated sky map files, which use a cylindrical equal-area projection with a standard latitude of -53.5 degrees.
Each hit-count-map pixel represents the effective number of samples contributing to the correspondent sky map pixel. During mapping, the first and last few seconds of each timestream were windowed with a 1/2*(1-cos) taper to avoid ringing in the Fourier transforms when computing the noise model. This leads to non-integral values in the hit-count maps. The provided FITS file contain 18787 by 1177, 0.25 square arcminute pixels.
A complete description of the observations, data processing, calibration, instrument response, and mapmaking process for this data release is in Dunner et al. 2012, arXiv:e-print.