[vsnet-grb-info 14340] GRB 131224B detected in ground analysis of Swift-BAT data

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15654
SUBJECT: GRB 131224B detected in ground analysis of Swift-BAT data
DATE:    14/01/02 23:45:09 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <james.r.cummings at nasa.gov>

J. R. Cummings and D. M Palmer (Los Alamos) report on behalf of the
Swift-BAT team:

At 03:25:08 while Swift was executing a pre-planned slew, BAT detected a rate
increase.  In ground analysis, a significant source was found at RA, Dec
163.722, -14.177 which is
RA (J2000)       10h 54m 53.3s
Dec (J2000)     -14d 10' 36"
with an estimated 90% confidence error radius of 3 arcmin.  This location
was about 95% coded in the BAT field of view during the burst.

The mask-weighted lightcurve shows two symmetrical peaks, the second peak
about 1/3 the size of the first, each about 4 seconds long and separated by
a gap of about 2 seconds.  T90 is about 9 seconds.

The average spectrum over 11 seconds is well fit by a simple power-law
function with a photon index of 2.09 +- 0.20.  The fluence was
(2.6 +- 0.3) x 10^-7 ergs/cm^2.  Errors are 90% confidence.

Because this burst was noticed a week after it occurred, there is no followup
planned with Swift.