Figure 3

Figure 3. X-ray energy spectra taken by the Berkeley germanium spectrometer. Note the significant flux of X-rays at MeV energies. The spectra harden slightly after 15:42 UT. The solid lines show the fit obtained from bremsstrahlung calculations with a model input of mono-energetic 1.7 MeV X-rays [Foat, et al., First Detection of a Terrestrial MeV X-ray Burst, Geophys. Res. Letters, 25, 1998].