HR diagram showing the locations of 11 red and yellow supergiants in the cluster, with their positions derived from the spectral classification, assuming a distance to the cluster d = 10 kpc (DM = 15.0). We also plot isochrones from Ekström et al. (2012). The dotted lines are the log t = 7.20 (16 Ma; top, cyan), and log t = 7.30 (20 Ma; bottom, pink) isochrones with high initial rotation. The solid lines are the log t = 7.08 (12 Ma; top, red), and log t = 7.20 (16 Ma; bottom, green) isochrones without rotation. The size of the symbols represents the errors in log L_∗ that are due to observational uncertainties and calibration problems. The errors in T_eff, though difficult to quantify, should be smaller than the symbol size.