Time–luminosity phase-space plot for radio bursts showing the product of observing frequency and pulse width (νW in GHz s) against the pseudoluminosity (S_pkd², left) and equivalent isotropic spectral luminosity (L_ν,iso = 4πS_pkd², right). The brightness temperature ﹩{T}_{{\rm{b}}}={(1/2{k}_{{\rm{b}}})\times ({{Sd}}^{2})/(\nu W)}^{2}﹩ is indicated by black lines with the nominal limit for coherent emission (T_b ∼ 10¹² K) shown as a thick black line. The shaded gray region at νW ≲ 10⁻⁹ GHz s is excluded due to the uncertainty principle. Pulsars (Manchester et al. 2005) and RRATs with known distances are shown in black and orange dots, respectively. Giant pulses from the Crab pulsar (Lundgren et al. 1995; Karuppusamy et al. 2010; Majid et al. 2011) and B1937 + 21 (McKee et al. 2019) are shown as green and purple lines, respectively, that indicate the range of pulse flux densities observed. The 0.4 ns Crab “nanoshot” (Hankins & Eilek 2007) is shown as a green dot. Bursts from the magnetar SGR 1935 + 2154 are shown as gray squares in a shaded gray box that indicates the extent of observed emission (Bochenek et al. 2020; CHIME/FRB Collaboration et al. 2020; Zhang et al. 2020; Kirsten et al. 2021b). FRBs with host galaxies with measured redshifts are also shown and labeled. For the repeaters FRB 121102 (Scholz et al. 2016; Spitler et al. 2016; Gajjar et al. 2018) and FRB 180916 (Marthi et al. 2020; Marcote et al. 2020), multiple bursts are shown. For FRB 200120E, we show the initial CHIME detection as a red circle (Bhardwaj et al. 2021), and our results as red crosses. DSN-B1 is the full 33 μs burst and DSN-C4 is the narrowest (∼100 ns) component of the burst.