Planck 2013 results. III. LFI systematic uncertainties

TL;DR

This paper assesses the systematic uncertainties in the Planck-LFI data, focusing on instrumental effects like sidelobe straylight and calibration, which are significantly weaker than the CMB signal but still require careful modeling and reduction.

Contribution

It provides a comprehensive estimate of systematic uncertainties for Planck-LFI, detailing methods to evaluate residuals and identifying dominant effects affecting the first cosmological data release.

Findings

Systematic uncertainties are mainly due to sidelobe straylight and calibration.

Residual signals are present at low multipoles, especially at 30 GHz.

Ongoing efforts aim to further reduce spurious signals and improve modeling.

Abstract

We present the current estimate of instrumental and systematic effect uncertainties for the Planck-Low Frequency Instrument relevant to the first release of the Planck cosmological results. We give an overview of the main effects and of the tools and methods applied to assess residuals in maps and power spectra. We also present an overall budget of known systematic effect uncertainties, which are dominated sidelobe straylight pick-up and imperfect calibration. However, even these two effects are at least two orders of magnitude weaker than the cosmic microwave background (CMB) fluctuations as measured in terms of the angular temperature power spectrum. A residual signal above the noise level is present in the multipole range $\ell<20$, most notably at 30 GHz, and is likely caused by residual Galactic straylight contamination. Current analysis aims to further reduce the level of spurious signals in the data and to improve the systematic effects modelling, in particular with respect to straylight and calibration uncertainties.