Updated calibrations of Galactic O-type stars

We present updated spectral-type-based calibrations of fundamental parameters for luminosity classes V, III, and I. Compared to previous works, we find systematic shifts, particularly in effective temperature for dwarfs and in Mv across all classes, which propagate into derived quantities. Applying the Mv calibrations to the full sample yields consistent estimates of radius and luminosity, while spectroscopic mass (Msp) shows significant scatter.

We also evaluate the FW3414 parameter (from the Hbeta line) as a calibrator for Mv, useful in large surveys lacking reliable spectral classification. Excluding SB1 systems has a noticeable impact only on the Msp calibration for LC V. These updated empirical calibrations offer a robust reference for Galactic O-type stars and will support studies of massive star populations in both Galactic and extragalactic contexts, particularly in the era of large spectroscopic surveys.