Initial vertical height of the explosion sites, grouped by galactocentric radius (star markers). Black dots denote the local galactic midplane; error bars the vertical scale height defined in the Appendix A. Radial coordinates, corresponding to R = 2,  4.5 and 8 kpc, were shifted for visibility. Even though the explosion sites were chosen to be close to z = 0, due to the warping of the disk, some of the SNRs are located outside the midplane.