Time evolution of flux density in VHS 1256−1257 at 6 GHz. Upper panel: points show the total flux density (Stokes I) averaged every 60 s, with a mean value of 78 μJy (plotted as a dashed line) and with a standard deviation of 37 μJy (plotted as a gray shadow). Lower panel: same as upper panel, but for Stokes V. The mean and standard deviation values in this case are 4 μJy and 38 μJy, respectively.