Top panel: for stars with τ_2.2 < 0.08, bolometric corrections BC_J are plotted versus T_eff values with black-filled circles. For stars with τ_2.2 > 0.08, gray crosses are plotted. The BC values were calculated with the M_bol inferred with the atmosphere models by Allard et al. (2011) and the DUSTY code and the absolute J magnitudes (from 2MASS). The dotted-dashed black line is the best polynomial fit of degree zero to the data points. The dashed green line is the theoretical BC_J inferred with Allard’s model ([M/H]=0, log(g)=0.5). The cyan squares mark the BC_J values estimated with an ATLAS9 grid of models and for Bessel filters by Howarth (2011) ([M/H]=0.0 and log(g)=0.5 dex); while our recalculations for the 2MASS filters are marked with red crosses. Middle panel: bolometric corrections BC_H versus T_eff values. Lines and symbols are as for the top panel. Bottom panel: bolometric corrections BC_Ks are plotted versus the T_eff values. Lines and symbols are as for the top panel. The dashed-orange line is the K-band relation for naked RSGs found with MARCS models and the K-filter profile of Bessell & Brett (1988) by Levesque et al. (2005).