We have investigated the relevant trend of the bolometric correction (BC) at the cool-temperature regime of red giant stars and its possible dependence on stellar metallicity. Our analysis relies on a wide sample of optical-infrared spectroscopic observations, along the 3500{AA}=>2.5um wavelength range, for a grid of 92 red giant stars in five (three globular + two open) Galactic clusters, along the full metallicity range covered by the bulk of the stars, -2.2<=[Fe/H]<=+0.4.

Cone search capability for table J/MNRAS/403/1592/table1 (Cluster properties and stellar database for globular cluster M15 (E(B-V)=0.10 [Fe/H]=-2.26))

Cone search capability for table J/MNRAS/403/1592/table2 (Cluster properties and stellar database for globular cluster M2 (E(B-V)=0.06; [Fe/H]=-1.62))

Cone search capability for table J/MNRAS/403/1592/table3 (Cluster properties and stellar database for globular cluster M71 (E(B-V)=0.25; [Fe/H]=-0.73))

Cone search capability for table J/MNRAS/403/1592/table4 (Cluster properties and stellar database for open cluster NGC 188 (E(B-V)=0.082; [Fe/H]=-0.02))

Cone search capability for table J/MNRAS/403/1592/table5 (Cluster properties and stellar database for open cluster NGC 6791 (E(B-V)=0.117; [Fe/H]=+0.4))