LOFAR measures the hotspot advance speed of the high-redshift blazar S5 0836+710 A. Kappes, M. Perucho, M. Kadler, P. R. Burd, L. Vega-García and M. Brüggen A&A, 631 (2019) A49 Published online: 17 October 2019 DOI: 10.1051/0004-6361/201936164