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GCN Circular 13039

Subject

GRB 120311A, Swift-BAT refined analysis

Date

2012-03-11T16:07:19Z (12 years ago)

From

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

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

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 120311A (trigger #517469)
(Markwardt, et al., GCN Circ. 13032Not found
 
 
).  The BAT ground-calculated position is
RA, Dec = 273.075, 14.297 deg which is
    RA(J2000)  =  18h 12m 18.1s
    Dec(J2000) = +14d 17' 49.0" 
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 71%.

The mask-weighted light curve shows a single gradual-rise exponential-decay
peak.  T90 (15-350 keV) is 3.5 +- 0.8 sec (estimated error including systematics).

The time-averaged spectrum from T-1.38 to T+3.22 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.30 +- 0.15.  The fluence in the 15-150 keV band is 3.0 +- 0.3 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T-0.07 sec in the 15-150 keV band
is 3.2 +- 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/517469/BA/