Spectrum of VHS 1256–1257 from VLA observations. The flux densities between 8 and 12 GHz correspond to the maps shown in Fig. 2. The upper bound resulting from the non-detection at L band is denoted with a downward arrow. The solid lines illustrate two possible spectra, each one made from a combination of the behavior predicted by the White et al. (1989) model of gyrosynchrotron emission (optically thick regime, showing the two extreme cases of α = 0.6: dashed line and 1.2: solid line), and a fit to our flux density measurements (optically thin regime, α = −1.1).