Top: HST/WFPC2-PC/F814W core of NGC 3603: blue squares depict the three fields observed with SPHERE-IRDIS. Green circles refer to the known O-type stars from Harayama et al. (2008). Red circles show the stars in Harayama et al. (2008) catalog, which we used for calibrating zero-points in different fields. There are 113, 45, and 51 stars common between Harayama et al. (2008) in the SPHERE F0, F1, and F2 fields. Bottom: sources with E(J−K) > 1.8 in F0, F1, and F2 shown in red circles. The image is a combination of all three fields in IRDIS/B-J.