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Atacama Cosmology Telescope (ACT)

Product Name
Temperature Power Spectra
Mission
ACT

Description

These files represent the beam transforms and radial profiles of the ACT beam, appropriate for use with the ACT 148 GHz and 220 GHz maps of 2008-2010 data. The beams are described in Hasselfield, Moodley et al. 2013.

The real space beam is the azimuthally averaged point spread function, normalized to 1 at theta=0, including the effects of pointing variance and the pixel aperture. The first column is the angle theta in degrees, and the second column is the beam amplitude.

The beam transform is the harmonic transform (on the sphere) of the azimuthally averaged beam. The Fourier space window functions is obtained by squaring the beam transform. The first column is the angular frequency, ell, and the second column is the beam transform normalized to 1 at ell=0.

The solid angle of the point spread function in the ACT maps (including the effects of pointing variation) vary for each season and array, and are described in Hasselfield, Moodley at al. 2013.

The beam fractional covariance matrix is also provided, decomposed into 10 modes. The covariance matrix is defined as an expectation value for the fractional beam uncertainty (delta B_ell / B_ell):

C_{ell,ell'} == < (delta B / B)_ell (delta B / B)_ell' >.

Covariant modes are found in files cov_modes_*.dat. In each file the first column is the multipole ell and the next ten columns are covariance modes E^i_ell. Considering the covariance modes as a 10001x10 matrix, the full covariance matrix C (10001 x 10001) is formed by the matrix product
C = transpose(E)*E.

The covariance includes uncertainty from the pointing variance correction.

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