The duration of the gamma-ray emission can be determined from any BAT light-curve using battblocks
. Note there are 2 x t in the name, battblocks; think of this as being short for BAT-Time.
>battblocks durfile=dur.gti bkgsub=yes countscol=TOT_RATE >Input data file name:sw00377487000msb.lc.gz >Output GTI file name: bb.gti ****************************************** battblocks v1.17 ------------------------------------------ Input Data: sw00377487000msb.lc.gz Output GTI: bb.gti Events to Skip: 128 Changepoint log(prob) Prior: 6.000000 Internal Tick: 1.000000e-04 s Lookback time: 0 s Bkg. Subtract?: yes (for fluence/T50/T90 calculations) ------------------------------------------ Estimated T90 duration: 4.096 s +/- 0.128 s Estimated T50 duration: 2.432 s +/- 0.128 s Estimated Peak Interval: MET 281296750.52800000 +/- 0.500000 s Estimated background rate 1: 6806.667 near MET 281296728.800000 s Estimated background rate 2: 6090.188 near MET 281296901.504000 s Estimated total duration: 135.488 s (for data selection) (from MET 281296731.200000 to MET 281296866.688000) Estimated total fluence: 3459.961958 count Created GTI with 9 entries ------------------------------------------
In this example, the *msb.lc light-curve has been used. This is the Swift onboard light-curve, which is telemetered to the ground via TDRSS. Thus, it will be located in the [obsid]/tdrss directory. See the BAT light-curve page for how to create your own light-curve, which can also be run through battblocks
.
The GTI file has been called bb.gti because it is computed using Bayesian Blocks.
If txx=67.0
is included on the command line, the time boundaries defining 67% of the fluence are given (printed to the screen and in the dur.gti file) as well as T90 and T50.