Notes. For each SN we report the host-galaxy name, the host-galaxy coordinates, the deprojected distance of each SN from its host-galaxy center (normalized by the De Vaucouleurs g-band radius of the host), and the absolute r-band magnitude as well as g − r color of the host galaxy. In the last six columns Z is reported for the host and at the SN position as measured from three different methods: (1) the luminosity-metallicity relation (LZ); (2) the luminosity-color-metallicity relation (LCZ); and (3) the strong-line diagnostic (O3N2; Pettini & Pagel 2004). When computing the metallicity at the SN distance from the host-galaxy center, we converted the average Z gradient in units of DeVRad_g^-1 by multiplying the metallicity gradient by 0.3, which is the typical ratio between DeVRad_g^-1 and the isophotal radius in the g-band. The isophotal radius, isoA_g, is available only for the SDSS galaxies in the DR7. The host of PTF10vdl is not detected, those of PTF09fma, PTF11hsj, and PTF11hzt are not in the SDSS footprint. We exclude these hosts from the analysis presented in Fig. 3. The vast majority of our SN hosts are in the optimal M_g − α(g − r) range where the LCZ relation was calibrated. The adoption of a standard gradient for all the host galaxies is a strong assumption and could lead to erroneous local metallicity estimates for some of the SNe if their actual gradient is significantly different from ours, as it could be for dwarf galaxies.