Relations between the total absolute fluxes and Teffare shown for dwarfs (open squares) and subgiants (gray circles). The solid black lines are the lower boundary of minimum chromospheric activity represented by the more inactive subgiants. The 1.5 M⊙ subgiants HD 36553 and HD 112164 are the only stars placed bellow the photospheric correction curve. The panels are divided for the three Ca II IRT lines. Left and middle panels stand for the T1 and T2 lines, and the right one ilustrates the behavior of the T3 line.