Bolometric correction in the 2–10 keV band as a function of the bolometric luminosity (left panel) and as a function of the 2–10 keV luminosity (right panel). Symbols for the WISSH quasars follow those of Fig. 4. Blue triangles indicate the broad-line AGN sample from the XMM-Newton-COSMOS survey by Lusso et al. (2012). The yellow squares indicate PG quasars; green symbols represent BAL AGN. The violet asterisks indicate the hyper-luminous quasars ULASJ 1539+0557, ULASJ 2315+0143, and 2QZ0028-2830. The black solid curve in the left panel represents the relation found by Lusso et al. (2012) for Type 1 AGN; the gray shaded area indicates the 1σ dispersion on the relation. As in Fig. 6, we report two values for the hard X-ray luminosity of J0045+1438 (i.e., the object with the lowest X-ray luminosity in the X-WISSH sample), connected by a gray line. We calculated the L₂₋₁₀ via the best-fit value of N_H (i.e., 4 × 10²² cm^-2, green open circle) and the upper error (i.e., N_H = 1.5 × 10²³ cm^-2, gray open circle), respectively.