Column density map of the Rosette molecular cloud, obtained from the 160, 250, 350, and 500 μm maps from Herschel. Known infrared-clusters are indicated in the plot as blue stars (“Pl” refers to Phelps & Lada (1997), A, B, etc. the clusters from Poulton et al. 2008), and labeling “Refl” those from Román-Zúñiga et al. 2008). White stars in the upper right corner indicate the O-stars from NGC2244.