Planck 2013 results. III. LFI systematic uncertainties

P.A.R. Ade, N. Aghanim, C. Armitage-Caplan, M. Arnaud, M. Ashdown, F. Atrio-Barandela, J. Aumont, C. Baccigalupi, A.J. Banday, Per Rex Christensen, Pavel Nasselski, Igor Dmitrievich Novikov, Hans Ulrik Nørgaard-Nielsen