Integrated UV flux of the core of R136. The upper panel shows the GHRS spectrum of the inner 2′ × 2′ (Heap et al. 1992; light blue crosses), as well as the summed STIS spectra used in this work (dark blue circles), with both covering roughly the same inner region of the cluster. The bottom panel shows the ratio of the former two spectra (yellow dots) as well as the central wavelength of the synthetic UV bands used in this work (red triangles, see Sect. 3.1). The dashed lines correspond to ratios of 0.75 and 1.25.