The systematic effects of photon flux on gamma-ray burst duration measurements

The duration of gamma-ray bursts (GRBs) represented by T90 and T50 was introduced as a means of measuring the duration of GRBs. We present a technique for calculating gamma-ray burst duration observed with the Gamma-ray Burst Monitor (GBM) onboard Fermi (formerly GLAST). We define the method for calculating the duration as the forward folding technique. We use time-profiles observed in a real burst to address the systematic effects on the duration of T90 and T50 in individual ways. We use T90 and T50 to show the impact of the systematic effects in those time distributions for the GRBs observed with the GBM. We discuss the variations in the different measurements among a large significant sigma > 3 in a 49 random sample of GRBs. We also give examples of GRBs in order to address the systematic effects in specific cases.