Number counts of the OTELO raw extended sources observed (open symbols) and corrected by completeness (filled symbols) according to the results presented in Sect. 5. Error bars are confined to Poisson statistics and the dashed line mark the 50% completeness limiting flux, which was adopted as the significance limit for the completeness correction. In comparison, blue stars and red crosses mark the faintest total number counts (corrected) reported by Kashikawa et al. (2004; z’-band; SDF) and Ouchi et al. (2010; NB-921; SXDS), respectively.