Transmission spectrum of WASP-19b as measured with FORS2 (black dots, with error bars) compared to two models of planetary atmospheres, one with no TiO (top panel) and one with a solar abundance of TiO (bottom panel), from Burrows et al. (2010) and Howe & Burrows (2012). We also estimated the mean value of the models in bin sizes of 20 nm (orange open squares). The dashed lines represent the weighted mean plus or minus three scale heights. Because of the overlapping spectral bins, only alternate pairs of transmission spectrum points contain unique information. The heavy, green bar on the left side shows the maximum error associated with unocculted spots.