a) Map of RCW 36; the same symbols as in Fig. 2 are used to classify the stellar population. Purple circles are the protostellar cores from MTHM13; according to these authors, core 1 contains over 20 M_⊙. The cyan cross marks the location of the UCHII (Walsh et al. 1998, W98). The SPIRE 500 μm contours are overplotted. b) Extinction map based on the JHK_s colors of individual stars (see text). The SOFI point sources are color-coded with their extinction values, overlain on the spatially smoothed extinction map. c) Same as a), zoom in on boxed region. d) Same as b), zoom in on boxed region. Symbols indicate the classified stars, color-coded with their extinction values obtained by spectral classification. e) Map showing the targets of which a spectrum was obtained and classified. f) SINFONI three-color linemap showing the different ionization properties of the nebula. Regions I–V (see text) are indicated. The symbols used in a), b) represent all classified sources; in c) all SOFI detections and d) only sources with a spectral classification. Figures a)–b) and c)–f) have the same scale, respectively.