Calibration mass and semi-major axis vs. orbital period. Left for SB1 and right for SB2. Top: Mass, the horizontal line marks the median mass. Bottom: Semi-major axis, the solid line marks a least-squares fit to the data (logarithmic, with the fit equation labelled). The vertical and horizontal lines are for guidance (dashed and dotted). Bottom right: Blue and red distinguish the mass ratio, the coloured numbers give the number of SB2s in the P_orb bins separated by P_orb = 10, 100, 1000.