Systematic effects on duration measurements of gamma-ray bursts

The parameters T-90 and T-50 have recently been introduced as a measurement of the duration of gamma-ray bursts. We present here a description of the method of measuring T-90 and T-50 and its application to gamma-ray bursts observed with the Burst and Transient Source Experiment (BATSE) onboard the Compton Gamma-Ray Observatory (CGRO). We use simulated as well as observed time profiles to address some of the possible systematic effects affecting individual T-90 (T-50) measurements. We show that these systematic effects do not mimic those effects that would result from time dilation if the burst sources are at distances of several Gpc. We discuss the impact of these systematic effects on the T-90 (T-50) distributions for the gamma-ray bursts observed with BATSE. We distinguish between various types of T-90 (T-50) distributions, and discuss the ways in which distributions observed with different experiments can vary, even though the measurements for commonly observed bursts may be the same. We then discuss the distributions observed with BATSE and compare them to those observed with other experiments.