The measured redshifts of gamma-ray bursts ( GRBs ) , which were first detected by the Swift satellite , seem to be bigger on average than the redshifts of GRBs detected by other satellites .
We analyzed the redshift distribution of GRBs triggered and observed by different satellites ( Swift \citep sak08 , HETE2 \citep van04 , BeppoSax , Ulyssses ) .
After considering the possible biases significant difference was found at the p = 95.70 \% level in the redshift distributions of GRBs measured by HETE and the Swift .