Herschel/SPIRE 250-μm far-infrared image towards the Orion B9 star-forming filament. The image is shown with a square-root scaling to improve the contrast between bright and faint features. The image is overlaid with black contours of SABOCA 350-μm emission. The SABOCA contours start at 3σ and increase at this interval (Paper III). The SABOCA data towards the IRAS 05399/SMM 1 -system with a 1σ noise level of 80 mJy beam^-1 are taken from Miettinen & Offner (2013). Selected cores are labelled. The ring-like structure comprising partly of SMM 6 is highlighted with a white dashed circle of radius or ~0.3 pc. A scale bar indicating the 0.3 pc projected length is shown in the bottom left corner.