Gamma-ray luminosity (0.1 − 100 GeV) vs. spin-down power of pulsars from the Third Fermi-LAT catalogue (adapted from Smith et al. 2023). The black diamond with error bars and the shaded grey area represent the 95% c.l. upper limit on the energy flux of the target, 6.8 × 10⁻¹³ erg s⁻¹ cm⁻², at a distance range of 0.7 − 1.5 kpc. The positions of the ‘three musketeers’ and Calvera are highlighted (see legend). The upper diagonal line shows where 100% of spin-down power is converted to gamma-ray flux, while the lower diagonal line represents the heuristic relation $L_{\gamma }\propto \sqrt{\dot{E}}$, for reference.