Verification of the ACS/HRC/G800L calibration correction from Figure 9. The main figure shows the observed SED of HD 47839, including low-resolution IUE spectrophotometry (small circles) in the UV (λ < 3000 Å), UBV (large circles), Strömgren uvby (triangles), and Geneva UB ₁B ₂V ₁G (diamonds) photometry in the optical (3000 Å <λ < 6000 Å), and RIJHK photometry in the NIR (λ>6000 Å). The smooth curve is a 37,000 K TLUSTY model atmosphere (Lanz & Hubeny 2003) fit to the data from (e.g., Fitzpatrick & Massa 2005a, 2005b). The inset illustrates the effect of the ACS/HRC/G800L correction curve shown in Figure 9. It shows the best fit model from the main figure (continuous curve) with the corrected and uncorrected G800L data (points) overplotted. For λ ⩽ 9500 Å the recalibrated data mimic the shape of the model SED, but lie ~1% above it, consistent with the scatter among the spectrophotometric standards. For λ ⩾ 9500 Å, the fluxes are clearly much less reliable