GCN Circular 6623
Subject
GRB 070714B, Swift-BAT refined analysis of the short hard burst
Date
2007-07-14T21:47:27Z (17 years ago)
From
Takanori Sakamoto at NASA/GSFC <takanori@milkyway.gsfc.nasa.gov>
L. Barbier (GSFC), S. D. Barthelmy (GSFC), J. Cummings (GSFC/UMBC),
E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC),
J. Racusin (PSU), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC), T. Ukwatta (GWU)
(i.e. the Swift-BAT team):
Using the data set from T-120 to T+182 sec from recent telemetry downlinks,
we report further analysis of BAT GRB 070714B (trigger #284856)
(Racusin, et al., GCN Circ. 6620). The BAT ground-calculated position is
RA, Dec = 57.853, 28.294 deg which is
RA(J2000) = 3h 51m 24.8s
Dec(J2000) = 28d 17' 37"
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 93%.
The BAT mask-weighted light curve shows multiple short spikes starting from
T-0.8 sec with a duration of 3 sec. There is extended softer emission from
T+20 sec to T+70 (and possibly T+100) sec. T90 (15-350 keV) is 64 +- 5 sec
(estimated error including systematics). The light curve looks similar to
previous short bursts such as GRB 050724 with a short-hard initial episode
followed by a softer extended episode, so we think it is likely that this
burst is in the short category.
The time-averaged spectrum from T-0.8 to T+65.6 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.36 +- 0.19. The fluence in the 15-150 keV band is 7.2 +- 0.9 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.39 sec in the 15-150 keV band
is 2.7 +- 0.2 ph/cm2/sec. Separating out the initial "spike" of emission
(from T-0.8 to T+2 sec), the photon index in a simple power-law fit is
0.99 +- 0.08. The fluence in the 15-150 keV band of this part is
5.1 +-0.3 x 10^-7 erg/cm2. All the quoted errors are at the 90% confidence
level.