H. Krimm (GSFC/USRA), L. Barbier (GSFC), S. D. Barthelmy (GSFC),
J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC),
C. Markwardt (GSFC/UMD), S McBreen (MPE), D. Palmer (LANL),
A. Parsons (GSFC), T. Sakamoto (GSFC/ORAU), G. Sato (GSFC/ISAS),
M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC)
on behalf of the Swift-BAT team:
Using the data set from T-2.3 to T+7.7 sec, we report further analysis
of BAT GRB 070406 (trigger #274153) (Cummings, et al., GCN Circ. 6247).
The BAT ground-calculated position is RA, Dec = 198.956, 16.530 deg
RA(J2000) = 13h 15m 49.3s
Dec(J2000) = 16d 31' 46"
with an uncertainty of 2.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 92%.
The lightcuve shows two peaks at T+0 and T+0.7 sec. The burst was very
faint in BAT, and additional peaks may be hidden in the noise.
T90 (15-350 keV) is 0.7 +- 0.2 sec (estimated error including systematics).
The time-averaged spectrum from T+0.0 to T+0.7 is best fit by
a simple power-law model.
The power law index of the time-averaged spectrum is 0.9 +- 0.4.
The fluence in the 15-150 keV band is 4.5 +- 1.0 x 10^-08 erg/cm2.
The 1-sec peak photon flux measured from T+0.00 sec in the 15-150 keV
band is 0.7 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90%