Measurement of the electric potential and the magnetic field in the shifted analysing plane of the KATRIN experiment. - KATRIN Collaboration; Aker, M.; Batzler, D.; Beglarian, A.; Behrens, J.; Beisenkötter, J.; Biassoni, M.; Bieringer, B.; Biondi, Y.; Block, F.; Bobien, S.; Böttcher, M.; et al. (European Physical Journal C -- Particles & Fields, 2024)