Top panel: radio spectrum of 1ES 2344+514 measured quasi-simultaneously by Effelsberg, OVRO and VLBA. The VLBA points represent integrated flux densities. The solid lines illustrate fits with a simple power law, the dashed line shows a broken power law fit. Bottom panel: fit residuals, which are the differences between the measured flux densities and the fit values divided by the flux density values. See also footnote ¹¹.