The reddened nebulosity in NGC 3603
Although stars are well known to form in clusters, most of the stars in the young groups we know of in our own galaxy are well separated in space. In NGC 3603 the stars are remarkably close together. Moreover, many of the stars in this compact constellation are Wolf-Rayet stars, extremely hot, massive objects, rarely found in such profusion in clusters. This curious collection of young objects is, as far as we know, unique in our galaxy, though the enigmatic object at the centre of the Tarantula Nebula in the Large Magellanic Cloud is now known to be a similar compact cluster. The stars and their associated nebula are seen through considerable dust along the line of sight, and are dimmed and reddened by it. 
AAO image reference AAT 40.
© Anglo-Australian Observatory, Photograph by David Malin, text © David Malin.

Entry from NGC 2000.0 (R.W. Sinnott, Ed.) © Sky Publishing Corporation, 1988: 

NGC 3576  Nb 11 11.8  -61 23 d  Car  20.         F, lE, 1st of 6                                    
NGC 3579  Nb 11 11.9  -61 14 d  Car              F, lE, sbM, 2nd of 6    
NGC 3581  Nb 11 12.1  -61 18 r  Car              *12 with fan-shaped neb att, 3rd of 6  
NGC 3582  Nb 11 12.3  -61 16 r  Car              B, bM*, 4th of 6                                   
NGC 3584  Nb 11 12.4  -61 12 r  Car              F, L, E 0deg , bM, 5th of 6                        
NGC 3586  Nb 11 12.6  -61 21 r  Car              eF, S, E 160deg +/- , 6th of 6
For details of photographic exposure, search technical table by AAT reference number

Related images
AAT 38 NGC 3576 and NGC 3603 in Carina
AAT 39 The loops of NGC 3576