Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 15620

GRB 131227A: Swift-BAT refined analysis
2013-12-27T15:00:28Z (10 years ago)
Scott Barthelmy at NASA/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),
C. B. Markwardt (GSFC), S. R. Oates (UCL-MSSL), 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+651 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 131227A (trigger #582184)
(Oates, et al., GCN Circ. 15616).  The BAT ground-calculated position is
RA, Dec = 67.369, 28.879 deg which is 
   RA(J2000)  =  04h 29m 28.5s 
   Dec(J2000) = +28d 52' 44.3" 
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 90%.
The mask-weighted light curve shows several overlapping peaks starting
at ~T-2 sec, peaking at ~T+2 sec, and ending at ~T+22 sec with a long low-level
tail out to ~T+100 sec.  T90 (15-350 keV) is 18.0 +- 1.6 sec (estimated error
including systematics).
The time-averaged spectrum from T-1.19 to T+19.23 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.36 +- 0.12.  The fluence in the 15-150 keV band is 8.4 +- 0.6 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+1.61 sec in the 15-150 keV band
is 1.1 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
The results of the batgrbproduct analysis are available at
Looking for U.S. government information and services? Visit