1° × 1° MSX 8.3 μm image overlaid with ¹²CO( J = 1–0) emission contours (Heyer et al. 2006), outlining the distribution of the ISM in the RMC. The small squares with sequence numbers denote the locations of Phelps & Lada (1997) IR clusters (except cluster PL7, which is off the MSX image). The large boxes outline the ACIS-I 17′×17′ pointings. The embedded clusters are clearly associated with the CO clumps and the dust-emission peaks. The center of the Rosette Nebula's ionizing cluster NGC 2244 is marked.