Upper: Photometric light curves from LAST (blue), ZTF-g (green), ZTF-r (red), DDOTI/OAN (orange) with temporal x-axis centered on the fitted peak time at MJD 60754.5. The magenta marker is the Swift-UVOT measurement in the UVW1 band. The dashed purple vertical line marks the arrival of IceCube-250421A. Lower: Pseudo-bolometric light curve in the (4700–6231 Å) range. The dot-dashed line shows the power-law fit of the early light curve decay after the peak (∝t^α, α = −0.43).