Monochromatic (ν = 2.42 × 10¹⁷ Hz) luminosity evolution of SN 2020bvc in the first 16 days. The dashed lines represent simulations of an off-axis (θ = 23 deg) X-ray afterglow characterized by a power-law circumburst density distribution ρ ∝ R^−k, with index k = 2.0 (orange), k = 1.5 (blue), and k = 0 (green). The X-ray data and upper limits of SNe Ic-BL, including SN 1998bw associated with GRB 980425, reported with squares and triangles, respectively, are from Margutti et al. (2014) and have been corrected for the (0.1–10 keV) energy range, assuming a power-law spectral model with photon index γ = 2. Also shown are the light curve of SN 2006aj associated with GRB 060218 (Campana et al. 2006).