Fermi/GBM detection efficiency for SGRBs. Panels (a) show the detection efficiency η_det, 3D for a fixed value of E_p, obs (reported on top of each panel) and different photon indices α (values shown in the legend), as a function of the 64 ms peak photon flux p_{[50 − 300]}. Panels (b) are obtained by averaging η_det, 3D over the observed distribution of E_p, obs (panel b.1), that of α (panel b.2), or both (panel b.3). In panels b.1 and b.2, the solid lines are contours of constant averaged η_det, 2D, with the values reported along each line.