Top: 15-year Fermi-LAT light curve of OP 313, divided into quiescent (blue) and flaring (yellow) states. The green line shows the time-weighted average flux of 4.93 × 10⁻⁸ photons/cm²s computed between 9 December 2014 and 9 August 2018. Bottom: Fermi-LAT photon index over the same 15-year period. The green line shows the average photon index computed between 9 December 2014 and 9 August 2018 (Γ = 2.39), with the green band indicating its corresponding 1σ uncertainty. The red vertical bands highlight the period in which LST-1 detected OP 313.