A Gamma‐Ray Burst Trigger Tool Kit

(Abbreviated) The detection rate of a GRB detector can be increased by usinga count rate trigger with many accumulation times Dt and energy bands DE, butthe nominal sensitivity is less important than how much fainter a burst couldbe at the detection threshold as Dt and DE are changed. Predictions of thedetection rate depend on the assumed burst population, which can be wildly inerror. I base the fiducial rate on the BATSE observations: 550 bursts per skyabove a peak flux of 0.3 ph/cm^2/s averaged over Dt=1.024s and DE=50-300 keV. Ifind that triggering on any value of Dt decreases the average threshold peakflux on the 1.024s timescale by a factor of 0.6. Extending DE to lower energiesincludes the large flux of the X-ray background, increasing the backgroundcount rate; a low energy DE is advantageous only for very soft bursts. Whethera large fraction of the population of bright bursts is soft is disputed; thenew population of X-ray Flashes is soft but relatively faint.Comment: To appear in the Ap.J., v.578. 12 pages text, 4 figures. Minor changes including discussion of burst statistic