Observed spectral energy distribution of the unresolved binary VHS 1256–1257AB from optical wavelengths through 1 GHz. The optical and near-infrared observed spectra (Gauza et al. 2015) are shown with a solid black line, while the photometric observations are plotted as pink symbols: solid circles stand for actual detections with S∕N ≥ 4 and arrows represent 4σ upper limits. The filter and passband names are labeled. The horizontal error bars represent the width of the filters. Also plotted is the BT-Settl photospheric model (gray line; Baraffe et al. 2015) normalized to the J-band flux of VHS 1256–1257AB. This model corresponds to a cool dwarf with solar metallicity, T_eff = 2600 K, and log g = 5.0 [cm s⁻² ], which are the parameters expected for an M7.5 source (0.06–0.072 M_⊙ ) with an age of a few hundred Myr (Chabrier et al. 2000).