GCN Circular 15205
Subject
GRB 130907A: Further Swift-BAT refined analysis
Event
Date
2013-09-09T19:41:01Z (12 years ago)
From
Hans Krimm at NASA-GSFC <hans.krimm@nasa.gov>
H. A. Krimm (GSFC/USRA), J. R. Cummings (GSFC/UMBC), D. M. Palmer (LANL),
C. B. Markwardt (GSFC) for the Swift-BAT team):
Using the complete data set from T-239 to T+963 sec, we report further analysis
of BAT GRB 130907A (trigger #569992) (Page, et al., GCN Circ. 15183). The
initial report on the BAT data was presented in Cummings, et al., GCN Circ. 15202.
The burst started while Swift was slewing from another target, and the burst
location came into the BAT coded field of view at about T-80 seconds. The
initial pair of peaks at T-117 that triggered Konus-Wind (Golenetskii, et al.,
GCN Circ. 15203) and INTEGRAL/SPI-ACS (Savchenko, et al., GCN Circ. 15204) were
seen from outside the coded field in the non-weighted rates.
The mask-weighted light curve is described in Cummings, et al., GCN Circ. 15202.
Although there are no discrete peaks later than T+240 seconds, the burst is
still detected in the mask-weighted rate out to T+963 sec, when this data cuts
off and continues to be detected onboard in a 64-second image starting at
T+1388, and possibly later. Since the BAT event data does not cover the full
extent of the burst, we cannot reliably calculate T90 at this point, but it is
at least 360 seconds.
The time-averaged spectrum from T-73.7 to T+767.4 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.17 +- 0.02. The fluence in the 15-150 keV band is 1.4 +- 0.01 x 10^-4
erg/cm2. We note that this time interval does not cover the entire burst
duration, so should be considered a lower limit.
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/569992/BA/