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We provide atmospheric parameters and rotational velocities of a large sample(~400) of O- and early B-type stars, analysed in a homogeneous and consistentmanner, for use in constraining theoretical models. Comparison of therotational velocities with evolutionary tracks suggest that the end of corehydrogen burning occurs later than currently predicted. We also show that thelarge number of the luminous blue supergiants observed in the fields areunlikely to have directly evolved from main-sequence massive O-type stars asneither their low rotational velocities or position on the H-R diagram arepredicted. We suggest that blue-loops or mass-transfer binary systems maypopulate the blue supergiant regime. By comparing the rotational velocitydistributions of the Magellanic Cloud stars to a similar Galactic sample wefind that (at 3sigma confidence level) massive stars (above 8Msun) in the SMCrotate faster than those in the solar neighbourhood. However there appears tobe no significant difference between the rotational velocity distributions inthe Galaxy and the LMC. We find that the vsini distributions in the SMC and LMCcan modelled with an intrinsic rotational velocity distribution which is aGaussian peaking at 175km/s (SMC) and 100km/s (LMC). We find that in NGC346 inthe SMC, the 10-25Msun main-sequence stars appear to rotate faster than theirhigher mass counterparts. Recently Yoon et al. (2006) have determined rates ofGRBs by modelling rapidly rotating massive star progenitors. Our measuredrotational velocity distribution for the 10-25Msun stars is peaked at slightlyhigher velocities than they assume, supporting the idea that GRBs could comefrom rapid rotators with initial masses as low as 14Msun at low metallicities.(abridged).

The VLT-FLAMES survey of massive stars: atmospheric parameters and rotational velocity distributions for B-type stars in the Magellanic Clouds