NuSTAR Observations of Gamma-Ray Burst Afterglows

NuSTAR's focusing X-ray optics provide unprecedented sensitivity above 10 keV, enabling late-time observations of gamma-ray burst (GRB) afterglows. To date NuSTAR has observed six GRBs: GRB130427A, GRB130925A, GRB150201A, GRB180720B, GRB190114C, and GRB190829A. While most NuSTAR data are consistent with the power-law spectra seen at lower energies, the multiple components seen in GRB130925A indicate the potential of late-time X-ray observations to reveal unexpected surprises.