Characteristics
BeppoSAX's Gamma-Ray Burst Monitor, operating in the energy range of 40–700 keV, recorded a fluence of (1.85 ± 0.3) × 10−6 erg/cm2 (1.85 ± 0.3 nJ/m2), and the Wide Field Camera (2–26 keV) recorded a fluence of (0.7 ± 0.1) × 10−6 erg/cm2 (0.7 ± 0.1 nJ/m2). BATSE (20–1000 keV) recorded a fluence of (3.1 ± 0.2) × 10−6 erg/cm2 (3.1 ± 0.2 nJ/m2).
About 5 hours after the burst the apparent magnitude of the object—a logarithmic measure of its brightness with a higher number indicating a fainter object—was 20.3 ± 0.3 in the U-band (the ultraviolet region of the spectrum) and 21.2 ± 0.1 in the R-band (the red region of the spectrum). The afterglow reached its peak luminosity in both bands approximately 2 days after the burst was first detected—19.6 ± 0.3 in the U-band at 02:13 UTC on May 11, and 19.8 ± 0.2 in the R-band at 20:55 UTC on May 10.
James E. Rhoads, an astronomer at the Kitt Peak National Observatory, analyzed the burst and determined that it was not strongly beamed. Further analysis by Frail and his colleagues indicated that the total energy released by the burst was approximately 5×1050 ergs (5×1043 J), and Rhoads determined that the total gamma-ray energy was approximately 3×1050 erg (3×1043 J). This implied that the gamma-ray and kinetic energy of the burst's ejecta were comparable, effectively ruling out those GRB models which are relatively inefficient at producing gamma rays.
Read more about this topic: GRB 970508