L_acc– calibration relationship. The black solid line traces the relationship derived in this study, while the orange dashed line represents the relationship by Gullbring et al. (1998). The data points represent the u-band excess luminosity and the accretion luminosity estimates inferred on an individual basis for a sample of 44 CTTS in our survey (see text). The error bars reflect the uncertainty on the individual T_spot estimates. The black dashed-dotted line shows the calibration line that would be inferred, with the procedure followed in this study, in the assumption T_spot = 10 000 K.