Projected rotation velocities and effective temperatures for the OB supergiants (red) and the O-type giants and dwarfs (blue) from our sample, plotted against evolutionary tracks from Brott et al. (2011). All stars have been binned into three mass ranges: 15 M_⊙ ≤ M ≤ 30 M_⊙ (bottom panel); 31 M_⊙ ≤ M ≤ 50 M_⊙ (middle panel), and M ≥ 51 M_⊙ (top panel). O-type stars close to the ZAMS with anomalously low vsini are additionally highlighted by asterisks. The large diamond marks HD 93843, which has been recently identified as a magnetic star (Hubrig et al. 2011). In the top panel, the most massive stars ( ≳ 70 M_⊙) are marked by crosses. The model values have been scaled by π/4 to account for projection. The two vertical lines represent the temperature limits of the bi-stability jump, as determined by Vink et al. (1999).