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GCN Circular 13899

Subject
GRB 121024A: Swift-BAT refined analysis
Date
2012-10-25T14:39:10Z (11 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
S. D. Barthelmy (GSFC), T. Sakamoto (AGU), 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), C. Pagani (U Leicester),
D. M. Palmer (LANL), G. Sato (ISAS), M. Stamatikos (OSU),
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 121024A (trigger #536580)
(Pagani, et al., GCN Circ. 13886).  The BAT ground-calculated position is
RA, Dec = 70.481, -12.255 deg, which is 
   RA(J2000)  =  04h 41m 55.5s 
   Dec(J2000) = -12d 15' 19.1" 
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 50%.
 
The mask-weighted light curve shows two overlapping peaks starting
at ~T-9 sec, peaking at ~T-7 and ~T+2 sec, and ending at ~T+6 sec
with a long low tail out to ~T+70 sec (and possibly out to ~T+130 sec).
T90 (15-350 keV) is 69 +- 32 sec (estimated error including systematics).
 
The time-averaged spectrum from T-8.27 to T+75.73 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.41 +- 0.22.  The fluence in the 15-150 keV band is 1.1 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+0.73 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/536580/BA/
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