Top: ρ Oph A observed at 870 μm with LABOCA (left) and at 350 μm with SABOCA (right). Offsets are in seconds of arc and units are in Jy/beam. The origin, (0, 0), is the same as in Fig. 1 and the numbers refer to Table 2. Middle: SABOCA data (left, purple contours), degraded to the 195 resolution of the LABOCA map (in colour). The colours show the IRAM map (right) of Motte et al. (1998), convolved to 195 resolution, and shifted to the position of the LABOCA origin. The LABOCA data are shown as purple contours. Bottom: observed spectral index α = Δlog I_ν/ Δlog ν for the wavebands 350 μm–870 μm (left) and 870 μm–1.3 mm (right).