Projected phase-space diagram, V_LOS vs. major axis distance from the centre of M 87, for all spectroscopically confirmed PNs from this work and Doherty et al. (2009).The major axis distance is given both in arcsec (bottom axis), and in kpc (top axis), where 73 pc = 1″. The PNs are classified as M 87 halo PNs (red asterisks) and ICPNs (blue asterisks), respectively; see text. Black squares identify spectroscopically confirmed PNs from Doherty et al. (2009). The smoothed 1, 2, and 2.5σ thresholds are represented by the dashed, dotted, and dot-dashed lines, respectively. The dashed horizontal line shows the M 87 systemic velocity V_sys = 1275 km s^-1 as computed in Sect. 3.2, while the continuous green line shows the effective radius R_e = 703.914″ determined by Kormendy et al. (2009). At V_LOS = −220 km s^-1, we plot the M 86 systemic velocity (long dashed line).