Average emissivity curve of BATSE gamma-ray bursts with different intensities

Six intensity groups with similar to 150 BATSE gamma-ray bursts each are co mpared using average emissivity curves. Time stretch factors for each of th e dimmer groups are estimated with respect to the brightest group, which se rves as the reference, taking into account the systematics of counts-produc ed noise effects and choice statistics. A stretching/intensity anticorrelat ion is found with good statistical significance during the average back slo pes of bursts. A stretch factor similar to 2 is found between the 150 dimme st bursts, with peak flux less than 0.45 photons cm(-2) s(-1), and the 147 brightest bursts, with peak flux greater than 4.1 photons cm(-2) s(-1). On the other hand, while a trend of increasing stretching factor may exist for rise fronts for bursts with decreasing peak flux from greater than 4.1 pho tons cm(-2) s(-1) down to 0.7 photons cm(-2) s(-1), the magnitude of the st retching factor is less than similar to 1.4 and is therefore inconsistent w ith stretching factor of back slope.