Near-UV transmission spectrum of HD 189733 b from the combined HST/STIS observations. The red symbols with error bars denote the systematics- and stellar spot-corrected transmission spectrum, their 1σ uncertainties, and the span of the spectral bins (the data is binned in wavelength over a resolving power of R = 50). The green symbols show our results when neglecting the stellar spot contamination in the analysis (symbols are slightly shifted in wavelength for visibility). The blue spectrum shows a theoretical model of the planet’s upper atmosphere (see Sect. 5.1) and the blue dots show the model integrated over the spectral bins. The orange curve shows an extrapolation from a fit to the optical–IR transmission spectrum of the planet (see Sect. 5.2).