Spitzer-IRAC colour composite image (blue-band1, green-band2, red-band-3) in a 1′ × 1′ field centred on IRAS 18345. The symbols °, ∗, X, +, □ and Δ show the locations of the source detected by WISE at 3.4 μm and 22 μm, Spitzer-MIPS at 24 μm and 70 μm, Beuther et al. (2002a) at 1.2 mm using IRAM 30-m telescope amd MAMBO, and Williams et al. (2004) at 850 μm using JCMT and SCUBA, respectively.