Comparing high-energy properties of GRBs in the BAT sample and metallicities of their host galaxies. High-energy properties of events plotted with circles are taken from Nava et al. (2012). The three events plotted with squares have their peak energy (i.e. the peak in νF_ν spectrum) outside the energy coverage of the BAT instrument: we estimated the peak by using the correlation between E_γ,peak and spectral index Γ, found by Sakamoto et al. (2009), and then computed E_γ,iso and L_γ,iso in the extrapolated 1–10 000 keV range (e.g. Pescalli et al. 2016).