TITLE: GCN CIRCULAR NUMBER: 6261 SUBJECT: GRB 070406, Swift-BAT refined analysis DATE: 07/04/09 14:09:15 GMT FROM: Jay R. Cummings at NASA/GSFC/Swift 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 which is 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% confidence level.