Maximal emission temperature $T$ for charged kaons in Pb$-$Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV as a function of the cube root of the charged-particle multiplicity density $\langle {\rm d}N_{\rm ch}/{\rm d}\eta\rangle^{1/3}$ Statistical uncertainties are shown as bars and systematic uncertainties are depicted as boxes.