  I compare the burst detection sensitivity of CGRO's BATSE, Swift's BAT, the
GLAST Burst Monitor (GBM) and EXIST as a function of a burst's spectrum and
duration. A detector's overall burst sensitivity depends on its energy
sensitivity and set of accumulations times Delta t; these two factors shape the
detected burst population. For example, relative to BATSE, the BAT's softer
energy band decreases the detection rate of short, hard bursts, while the BAT's
longer accumulation times increase the detection rate of long, soft bursts.
Consequently, Swift is detecting long, low fluence bursts (2-3x fainter than
BATSE).
