Using Eq. (4) and the numerical values quoted in Sect. 4.2 of the Paper, which are all correct, the derived distance r should read 4 kpc ≤ r ≤ 16 kpc instead of 9 kpc ≤ r ≤ 37 kpc, i.e. roughly a factor 2 smaller. Accordingly, the distance quoted in Sect. 5 and in the Abstract should read r 10 kpc instead of r 20 kpc. This error does not affect any of the conclusions of the Paper. We thank John Everett for bringing this error to our attention.Article published by EDP Sciences and available at