GRB 130831A: X-ray to optical SED of the AG at t − t₀ = 0.39 and 1.12 d (observer frame). A single PL provides a good fit to both epochs of data (β = 0.85 ± 0.01 and 0.75 ± 0.06 respectively). For the first epoch (left) we find A_V < 0.1 mag (90% CL), while in the second epoch (right) we find mag. The results of the SED fitting indicate that the rest-frame extinction is consistent with being A_V = 0.0 mag. Additionally, we find the intrinsic column density to be N_H ≈ 3−4 × 10²⁰ cm^-2 for both epochs.