Abstract
A sample of 427 gamma-ray bursts (GRBs) was observed by the RHESSI satellite in Feb. 2002 - Apr. 2008. We calculated spectral lags and peak-count rates for the first time and constructed a new observational database.
This database is statistically studied completing an earlier analysis of durations and hardness ratios. First, we discuss properties of short-, intermediate-, and long-duration GRBs in terms of peak-count rates and spectral lags.
Second, we investigate the number of GRB groups using model-based clustering method together with Kolmogorov-Smirnov (K-S) and Anderson-Darling (A-D) tests. The results are: The inter. bursts have properties similar to short bursts.
The groups of inter. and long bursts appear to be different. The inter.
GRBs in the RHESSI and Swift databases seem to be different phenomena. This work is summary of Řípa et al. (2012).