Abstract
This paper describes the mapmaking procedure applied to Planck Low Frequency Instrument (LFI) data. The mapmaking step takes as input the calibrated timelines and pointing information. The main products are sky maps of I, Q, and U Stokes components. For the first time, we present polarization maps at LFI frequencies. The mapmaking algorithm is based on a destriping technique, which is enhanced with a noise prior. The Galactic region is masked to reduce errors arising from bandpass mismatch and high signal gradients. We apply hornuniform radiometer weights to reduce the effects of beamshape mismatch. The algorithm is the same as used for the 2013 release, apart from small changes in parameter settings. We validate the procedure through simulations. Special emphasis is put on the control of systematics, which is particularly important for accurate polarization analysis. We also produce lowresolution versions of the maps and corresponding noise covariance matrices. These serve as input in later analysis steps and parameter estimation. The noise covariance matrices are validated through noise Monte Carlo simulations. The residual noise in the map products is characterized through analysis of halfring maps, noise covariance matrices, and simulations.
Original language  English 

Article number  A6 
Number of pages  23 
Journal  Astronomy and Astrophysics 
Volume  594 
DOIs  
Publication status  Published  1 Oct 2016 
MoE publication type  A1 Journal articlerefereed 
Keywords
 Cosmic background radiation
 Methods: data analysis
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Metsähovi Radio Observatory
Joni Tammi (Manager)
School of Electrical EngineeringFacility/equipment: Facility