Colour composite of the field of NGC 3603, with Sher 25 marked by the crosshairs. The centre shows a semi-transparent Hubble Space Telescope Wide Field Camera 3 (HST/WFC3) image (proposal ID: 11360, PI: Robert O’Connel) with the following colour coding: blue (F656N filter), green (F673N), yellow (F128N), and red (F164N). The background shows a 2MASS colour image composed of J (1.235 µm, blue), H (1.662 µm, green), and K_s exposures (2.159 µm, red).