Best-fit power-law models (with EBL absorption in Fermi-LAT and neutral hydrogen absorption for NuSTAR and Swift-XRT) fitted to each dataset with native tools (xspec or Fermitools depending on the case) and gammapy. For reference, the spectral reconstruction with the OFF Background estimate in NuSTAR (second panel) is shown in blue for reference. Upper limits are calculated at a 95% confidence level from the cstat/wstat likelihood profiles.