Spectral energy distribution of prompt emission during the early optical observations of GRB 221009A taken with the all-sky camera at the Mondy telescope. The shaded blue region represents the uncertainty associated with the spectral parameters of the prompt emission. The Fermi spectrum (T₀ +40 to T₀ +120 s) during the Mondy observations, characterized by the best-fit Band function, is from Ror et al. (in prep.).