Best-fit SED models for RS Oph (black; this work, t − t₀ ∼ 1 d), V906 Car (grey; Aydi et al. 2020), the first novae detected with Fermi-LAT (V407 Cyg, orange; V1324 Sco, green; V959 Mon, brown; V339 Del, pink; Ackermann et al. 2014), and the expected SED from T CrB (blue). The solid region of the nova SEDs approximately corresponds to the energy range where the model was fitted to the data, while the spaced-dashed region corresponds to the extrapolation region of the model. In addition, the sensitivity curves for LST-1 at low zenith angles (zd < 35 °; red square curves; Abe et al. 2023a) and the four LSTs of CTAO-North at zd = 20° (purple circle curves; using the latest Prod5-v0.1 IRFs in Cherenkov Telescope Array Observatory & Cherenkov Telescope Array Consortium 2021) for 5 and 50 hours of observation time (see text for details) are displayed as solid and dotted curves, respectively.