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GCN Circular 13692

Subject
GRB 120817B: BAT location in ground analysis and refined analysis
Date
2012-08-20T14:35:48Z (12 years ago)
From
Jay R. Cummings at NASA/GSFC/Swift <james.r.cummings@nasa.gov>
J. R. Cummings (GSFC/UMBC), S. D. Barthelmy (GSFC),
W. H. Baumgartner (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), M. Stamatikos (OSU),
J. Tueller (GSFC), T. N. Ukwatta (MSU)
(i.e. the Swift-BAT team):

At 04:02:29 on August 17, 2012, Swift-BAT triggered (BAT trigger # 531259) on
the IPN burst GRB 120817B (Golenetskii et al., GCN Circ # 13670).  No source
was found onboard.  In ground analysis of the failed-trigger event sample, a
significant source was found at RA, Dec 8.310, -26.428, which is

RA (J2000)   00h 33m 14.4s 		
Dec (J2000)  -26d 25m 42s

The estimated 90% confidence position error is 2.8 arcmin radius.  This
position was 5.5% coded in the BAT FOV.  It is 5 arcmin from the center of
the IPN triangulation, within the IPN error box.

As seen in BAT, the burst was a single spike 0.10 +/- 0.02 seconds long.

The time-averaged spectrum from T+0.2 to T+0.3 sec is best fit by a simple
power-law model.  The best-fit photon index is 0.60 +/- 0.3.  The total
fluence in the 15-150 keV band was (1.7 +/- 0.4) x 10^-7 ergs/cm^2.  The
errors quoted are at the 68% confidence level.
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