KERRBB disk bolometric luminosity (in units of erg/s) as a function of the viewing angle of the disk, in the cases with a = −1, a = −0.6, a = 0.6 and a = 0.998, with Ṁ = 10¹⁸ g/s. The fitting function (blue line) has the general form of (8) with different values for the parameters, in the different cases. We note the different behaviors: in the cases a = −1, − 0.6 and 0.6, the bolometric luminosity, between the cases 0^° and 85^°, decreases by a factor of ~7, 6.6 and 4.4, respectively. In the case with a = 0.998, the luminosity reaches a maximum value at ~64^° (see Table 1) then drops at larger viewing angles.