100 μm/0.22 μm flux ratio map of the GRB 980425 host. The image is 35′′ × 35′′ and is constructed from images adaptively smoothed to the same spatial scales using Asmooth (Ebeling et al. 2006) to avoid strong colour fluctuations. The contours represent the narrow-band Hα map (grey, confirmed to be consistent with the IFU Hα image from Christensen et al. 2008) and R-band image (red; Sollerman et al. 2005). The black circle shows the GRB position. The WR region is to the north-west of this position. It is apparent that the low 100 μm/ NUV flux ratio (blue regions) corresponds to the spiral arms traced by star-forming regions (peaks of red and grey countours), with the exception of the WR region exhibiting very high 100 μm flux.