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GCN Circular 15521

Subject

GRB 131127A, Swift-BAT refined analysis

Date

2013-11-27T20:49:44Z (10 years ago)

From

Craig Markwardt at NASA/GSFC <craigm@milkyway.gsfc.nasa.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), J. R. Cummings (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (NASA/UMBC),
D. M. Palmer (LANL), T. Sakamoto (AGU), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):

Using the data set from T-240 to T+960 sec from the recent telemetry 
downlink, we report further analysis of BAT GRB 131127A (trigger 
#579571) (Markwardt, et al., GCN Circ. 15516Not found
 
 
).  The BAT 
ground-calculated position is
RA, Dec = 332.714, 36.596 deg which is
    RA(J2000)  =  22h 10m 51.3s
    Dec(J2000) = +36d 35' 46.9"
with an uncertainty of 1.8 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 39%.

The mask-weighted light curve has multiple peaks.  The first set of 
about 3 peaks occurs before the initial trigger between T-60 and T-38 
sec.  The main set of about 7-8 peaks occurs between T-5 and T+40 sec. 
The peak emission occurs at about T+0 sec.  T90 (15-350 keV) is 92.1 +- 
10.2 sec (estimated error including systematics).

The time-averaged spectrum from T-59.4 to T+37.5 sec is best fit by a 
simple power-law model.  The power law index of the time-averaged 
spectrum is 2.34 +- 0.16.  The fluence in the 15-150 keV band is 1.9 +- 
0.2 x 10^-6 erg/cm2.  The 1-sec peak photon flux measured from T-0.54 
sec in the 15-150 keV band is 1.3 +- 0.2 ph/cm2/sec.  All the quoted 
errors are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
   http://gcn.gsfc.nasa.gov/notices_s/579571/BA/