Multiwavelength light curves of GB6 J2113+1121. In the monthly γ-ray light-curve panel, the horizontal and black dashed vertical lines are the same as those in Figure 1. For the Swift-UVOT measurements, corrections of the Galactic absorption have been carried out (Cardelli et al. 1989; Schlafly & Finkbeiner 2011). For the ZTF light curves, the solid markers represent the magnitudes of the target, while the hollow ones correspond to average values of the comparison stars in the same field. The red vertical line across all panels marks the arrival time of the neutrino.