Core-shifts and proper-motion constraints in the S5 polar cap sample at the 15 and 43 GHz bands F. J. Abellán, I. Martí-Vidal, J. M. Marcaide and J. C. Guirado A&A, 614 (2018) A74 Published online: 15 June 2018 DOI: 10.1051/0004-6361/201731869