Spectral Cross-Calibration of Fermi-GBM and INTEGRAL-ISGRI using Gamma-Ray Bursts

摘要

We present an extended cross-calibration study between the Fermi Gamma-Ray Burst Monitor (GBM) and the INTEGRAL Soft Gamma-Ray Imager ISGRI. A previous sample contained 4 GRBs; GRB081226B; GRB090107B; GRB090625B and GRB090704. A long burst detected by both instruments, GRB090817, provides us with the opportunity to further test the agreement between the previous sample and the new data. GRB090817 contains significant telemetry gaps in the ISGRI data set and methods were devised to account for these gaps. The combined datasets from both instruments for GRB090817 were fit with 3 separate spectral models - a Power Law (PL), Cut-Off Power Law (COPL) and a Band model. The best fit joint spectral model is shown for the time averaged and time resolved joint spectral fits. As a measure of relative flux between the two instruments, a normalisation constant was calculated from the joint spectral fitting.