These files contain estimated Fourier-domain filter transfer functions (TFs) for South Pole Telescope (SPT) maps of the ra5h30dec-55 field observed during the 2008 season in the 150 GHz and 220 GHz bands, produced for the first SPT data release in December 2011. They are to be used with the associated map files, which use the oblique Lambert equal-area azimuthal projection.
The transfer functions are constructed by simulating observations of a map with a single Gaussian source with a FWHM of 0.75 arcminutes centered at pixel [1559,1559], and subjecting those simulated observations to the data processing and filtering used for real SPT data. The input signal is then divided out from the Fourier-domain representation of the resulting maps. Regions of the Fourier plane for which the Gaussian kernel amplitude was less than 1% were set to zero to avoid numerical artifacts. The transfer functions are stored in the primary image arrays of FITS files as 3120-pixel by 3120-pixel grids, where the grid in each dimension corresponds to 0, 2pi/(NT), 2*2pi/(NT), ... (N/2-1)*2pi/(NT), 2pi/(2T), -(N/2-1)*2pi/(NT), ..., -2pi/(NT) where N is the number of elements (3120) and T is the sampling interval in each dimension of the map (0.25 arcminutes).
Each file contains the transfer function estimated for a subregion of the map covering approximately one-ninth of the map area. The transfer functions are stored in the primary image arrays of FITS files. The two numerical tags in the file names (as well as the X_CEN/Y_CEN and RA_CEN/DEC_CEN keywords in the files) refer to the pixel locations in x and y at the location of the Gaussian kernel and the center of the mask used to define the subregion.
A complete description of the observations, data processing, calibration, instrument response, and mapmaking process for this data release is in Schaffer et al. 2011, ApJ, 743, 90.