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tokens: Swift Observatory short GRBs suggests that of those with an X-ray afterglow, >30% have evidence for additional energy input at later times, most commonly in the form of a long-lived plateau, persisting at bright levels for hundreds to thousands of seconds (with the majority at the shorter end), or in the form of X-ray flares. Such properties are also common in long GRBs and are widely ascribed to additional energy injection. The origin of the prompt emission in GRB 170817A is difficult to explain with an off-axis-viewed typical short GRB (Kasliwal et al. 2017 ; Lamb Kobayashi 2018 ); however, some component of the observed GRB could be due to emission from the midpoint of a structured jet (Ioka Nakamura 2019 ). The required core energy and Lorentz factor are at the upper limits for the short GRB population but consistent with those from afterglow modeling assuming a Gaussian-structured jet (e.g., Gill Granot 2018 ; Lamb et al. 2019a ; Troja et al. 2019b ). For the refreshed shock models shown here, the top-hat jet structure, the initial on-axis isotropic equivalent kinetic energy ∼10 51 erg, and the separation of ι / θ j ∼ 3 for both models suggest 10 10 If we assume a typical γ -ray efficiency η γ ∼ 0.15, where , and following the method in Ioka Nakamura ( 2019 ) and including the opacity for high-energy photons as in Lamb Kobayashi ( 2016 ), we find an isotropic equivalent γ -ray energy for an observer at ι = 0.28(0.31) rad of erg and ∼2.5 × 10 38 erg for Models 1 and 2 respectively, with spectral peaks at E p ∼ 0.55 (0.23) keV, and well below the erg and E p ∼ 185 ± 62 keV for GRB 170817A. that the prompt emission of GRB 170817A is better explained as the shock breakout from a cocoon of material that is inflated by the successful, ultrarelativistic jet (Bromberg et al. 2018 ; Duffell et al. 2018 ; Gottlieb et al. 2018b ; Pozanenko et al. 2018 ). Then, GRB 170817A is more a “burst of γ -rays” than a “classical” GRB (Kasliwal et al. 2017 ). An interesting result of the posterior distribution from Model 1 for the Lorentz factor of the initial outflow is the preference of the model for “lower” values, see Figure 5 . Given the energy of the initial outflow, erg, any dissipation within an outflow with Γ 0,1 ≲ 25 is likely to be into an optically thick medium, resulting in a failed GRB (Dermer et al. 2000 ; Huang et al. 2002 ). This implies that GRB 170817A may be associated with a population of failed GRBs that would result in on-axis orphan afterglows for all but the nearest events where the burst of gamma rays from the shock breakout may be detected. Such a population could dominate the neutron star merger population; however, at cosmological distances the electromagnetic counterparts, even for an on-axis observer, would be difficult to detect (Lamb Kobayashi 2016 ). However, if we restricted the prior range for the initial Lorentz factor to Γ 0,1 ≳ 25, then higher Lorentz factor solutions to the fit exist, with some at Γ ≳ 100 (see the top